Is It Ethical?

[mevinyavin]

IMHO if it will cause them tzar, you don't have the right to bring it up even if it is your chiyuv to return the money. Sounds similar to the machlokes about asking someone for mechila for LH you said about them when they don't even know you said it, though there it is a machlokes anyway, and also here it isn't your fault. But I would think if tzar would be caused you would have to find a different mehalech.
I might be able to ask a posek in a few minutes. Stay tuned.

ETA: R' Berkovits said that since the money wasn't gezel when you got it, you aren't mechuyev to return it in a way that they are aware of it. So he said you can find a way of getting them the money that qualifies as mishtamer (not just leaving it out, such as perhaps putting it in their bank account). He said you shouldn't return the money directly if it will be meorer tzar.

[aygart]

Is it clear that Halacha requires the money to be returned?

[mevinyavin]

Is it clear that Halacha requires the money to be returned?

Dunno. That's what he said, though. If anything you may be able to take only peol botul like the botei din paskined during corona, but I was also wondering about this over Shabbos and I plan on following up when I get the chance.

[yerushabubby]

I am not at all sure whether I am required to return it, but I don't feel comfortable keeping it.  I will try to find a way to return it indirectly, although at the moment I am not sure how to go about doing so.

[Definitions]

I wouldn't return it indirectly, although I don't either know the best way to return it to minimize them getting hurt. But I definitely would return the whole sum.

[YitzyS]

I think that the best way to get it back to them is during a conversation about the child. You can stop by the house and tell them that you started a new initiative in the group Le'ilui Nishmas the child, such as answering Amen or making brachos out loud. You can show them pictures of the initiative in action, with pictures of the signs you hung up. If applicable, you can also say over a nice story about the kid, or something else about them that was special. Then, as a 'by the way', you can mention that you have the money and you would want to return it, but if they'd rather, you can use it for something that would be le'ilui nishmas the child.

By doing this, you can bring a nechama in some way to the family, who see that the memory of their child is being honored. Although that may be bringing up pain, I doubt that is the wrong thing to do. And then you can take care of the money as a side point, which is doubtful to cause more pain. It's totally different than just calling them up and saying "hey, here's back your money because your kid died."

But again, maybe run this by Daas Torah. BH, I have little personal experience with grieving, so I cannot say what it feels like to be in that situation.

[aygart]

I am not at all sure whether I am required to return it, but I don't feel comfortable keeping it.  I will try to find a way to return it indirectly, although at the moment I am not sure how to go about doing so.

If you do not need to return it then you can use it to do something or dedicate something in the child's memory.

[ckmk47]

At some point the parents are going to note to themselves that they prepaid for the month. 
I think you should return it with a warm note saying how cute she was and how much you enjoyed having her.
If you have an anecdote or pictures (perhaps she was too young for that) include it. 
Like menachem avel, which you presumably did.

[mevinyavin]

Is it clear that Halacha requires the money to be returned?

C"M posek I spoke to this morning says you definitely don't have to return it (machlokes poskim=whoever is the muchzak). However, when I spoke to RYBs he never mentioned this possibility. Maybe he was operating on the assumption that you wanted to return it.
Either way, I read the posts about returning it in a nice way, but R' Berkovits was clear: if you have any chshash at all that pain will be caused, you cannot return it. If, on the other hand, any of the above suggestions are guaranteed to not cause pain (I guess we can't estimate this for you), I suppose you could.

[yerushabubby]

Thank you to everyone for the ideas - I will have to see what will work best.

[yfr bachur]

not exactly an ethics issue, but rather a dilemma -

I was watching a child who was unfortunately niftar.  The parents already paid me for the month, but the child was niftar before the first work day of that month,  I would like to return the money, but a friend is concerned that it may cause more tzaar to the parents - the last thing that I would want to do!  Does anyone have any ideas on how I can return the money without causing them more pain?

As a father who buried an infant, I think that

At some point the parents are going to note to themselves that they prepaid for the month. 
I think you should return it with a warm note saying how cute she was and how much you enjoyed having her.
If you have an anecdote or pictures (perhaps she was too young for that) include it. 
Like menachem avel, which you presumably did.

is the correct approach.
I can't speak for other people, but I can't see why it should give more pain.

[yerushabubby]

not exactly an ethics issue, but rather a dilemma -

I was watching a child who was unfortunately niftar.  The parents already paid me for the month, but the child was niftar before the first work day of that month,  I would like to return the money, but a friend is concerned that it may cause more tzaar to the parents - the last thing that I would want to do!  Does anyone have any ideas on how I can return the money without causing them more pain?

The mother stopped by today to thank me for taking care of her baby, so I gave her the envelope with my condolences.  Thank you everyone for your helpful advice and comments!

[chinagel]

Bought a battery from AutoZone. Ended up not needing it. When I tried to return, they claimed it was installed so they can't accept. (From speaking to others, it seems this is there way of doing business.)
Grounds for a dispute? It most definitely was not installed.

[JMHO]

Bought a battery from AutoZone. Ended up not needing it. When I tried to return, they claimed it was installed so they can't accept. (From speaking to others, it seems this is there way of doing business.)
Grounds for a dispute? It most definitely was not installed.

Why not?

[chinagel]

Why not?

IDK. Is denying a return grounds for dispute?

[YitzyS]

Bought a battery from AutoZone. Ended up not needing it. When I tried to return, they claimed it was installed so they can't accept. (From speaking to others, it seems this is there way of doing business.)
Grounds for a dispute? It most definitely was not installed.

Is your question about the store or the credit card company?

If it's the store, I think it depends on their policy. If they accept returns and now they are not, I think it's fair game for a dispute.

If your question is about the credit card company, you can always call them and ask them outright if this story qualifies for a dispute.

[etech0]

Is your question about the store or the credit card company?

If it's the store, I think it depends on their policy. If they accept returns and now they are not, I think it's fair game for a dispute.

If your question is about the credit card company, you can always call them and ask them outright if this story qualifies for a dispute.

And if it's amex, you could also ask if it would qualify for return protection