Cognac, can you help by showing your nephew how to look for scholarships online? Also, his high school probably has lots of scholarship information and most high schools use a website that keeps track of their SAT scores and lets them search for potential schools. Maybe you can convince his mother to fill out the free FAFSA form which would help him quality, maybe, for financial aid.
You're a great aunt but it's really unfortunate that his mother's desire to keep him away from college may put more work on you if you decide you can help out.