That's too bad. Well, I wish you luck in finding them homes. Kittens are usually easy to place, it's the adults that can be a problem!
sadly momma cat was killed and found yesterday morning, 2 of the babies are placed, there is another litter by another momma cat, so we still need plenty of homes. the nursing of baby kittens isn't over yet.
CAT
If they're young enough you can try your local petco. Many of them here will take them and sell them as long as they're healthy. It's not the best answer, but it beats some of the other options.
I agree with April. You are doing the best possible things for them. The mother has been living on her own, and can't live in a human home, so spay and release is best for her. If you can find indoor homes for the kittens, as April recommends, it will be better than placing them with rescue or humane society, as they have more kittens than they can find homes for.
Your daughter is doing a good work.
What I did when I was fostering a mama cat and kittens was took an ad out and charged $10 a kitten. That was just enough to cover the cost of the ad. I had an overwhelming amount of callers on them. I was careful to screen people to make sure they went to a good home. One person who called didn't even ask what they looked like or gender or anything so I didn't let him come over. I told him they were all gone. Just got to go with your gut instinct!
Anyway, that's something to think of. You always have Craigslist too.
I think what you guys are doing is wonderful. I wish there were more people like you in the world! :) God bless you both.