Are they grants available for children with mother's in federal prison?

For what purpose, college? There are college scholarships for just about everything imagineable. There are also scholarships for kids who are the first in their family to get a college education, if that might apply, and a lot based on financial need which would probably apply if the parent is in prison. And besides published scholarships, each school offers all kinds of funding resources so you have to talk to the individual schools.

And don't go just based on published tuition. I have found with kid that the private schools are able to offer so much private money to him that the most expensive school he looked at is the cheapest in the long run. They are giving him money for all different things from grades to financial need and several things in between.

There are no grants for children just because parent is in prison,

What is the money for ?