I agree with play and learn ~ do you have non refundable deposit in your contract? If so, then no.

I have it written in my contract as my deposit is one week, non refundable to help advertise if a family backs out and it also is my client's first week of care.
I would advise her that you understand why she has decided to not have the kids come. Having said that you also have to now advertise for 2 spots which requires more time and money