Depends on the mom but...
Weekend away with the whole family at a rented house with some planned games and activities and just enjoying being all together.
And as cliche as it is a nice put together video with pictures and home movies is always great IMHO.
Catered (or potluck) Family dinner at someone's house or restaurant.
Family and friend's party.
A planned trip for her and spouse/friend/kids.
Fam/friends dinner with a hired magician, singer, or (my favorite) hypnotist.
Gift a nice piece of artwork. Or personalized artwork.
Shutterfly Book with pictures and letters from family and friends.
Tickets to a favorite performer.