Sounds like a bad deal on both ends, IMO. Sounds bad for a family to be advertising that they're looking for someone to effectively adopt their kids for two weeks. Almost as crazy as what half the working world does, by having their kids raised by their Spanish cleaning lady/babysitter.
Also an bad deal for anyone taking it. If I'd advertise "Looking for a live in maid, wages are the accommodations", I don't think I'd get too many takers.
On that note, kudos to them for screening their offers carefully. Many people (including the aforementioned whose children are raised by their cleaning ladies) don't get around to doing that.