You are now seeing that it is going to be pretty much impossible to get to anywhere near 20K/yr. The only way that you might have been able to have gotten a cost of attendance that low is if your child were to have been accepted by one of the most generous schools, which are also the most selective, and that appears to be extremely unlikely.
So, the options are to get the grandparent to pay, or to take out substantial loans, or to start at a community college. With your child having no experience of group classroom learning in high school, I strongly urge you to consider the community college to in-state flagship U route. People with ADHD do better being taught one-on-one; it’s going to be an adjustment for her, best accomplished in the less challenging setting of a community college. Your child should also be able to do some dual enrollment coursework starting in January, possibly for free since she’ll still be in high school. That combined with some CLEP courses which she can start now, self-studied via modernstates.org, plus officially starting community college in the summer term, would probably enable her to be at your flagship state U or another 4 yr in-state public college by Sept '25, with junior standing. You would have to do some research to find out which CLEP exams the community college is likely to accept, and whether the flagship state U would accept these credits as part of an associates degree before transfer. She might be able to keep the cost of her BA or BSN to under the 80K total you think you can contribute, and she can still take out 27K in federal loans, if necessary.