I need some real help.

So my best friend ran away from home, and no one can find her. She had a pretty good reason. Everyone in school terrorized her and her parents both left. She was living with her grandma who was trying to shove religion down her throat. I'm still somewhat in contact with her, but because I know why she did it and that shes in good hands, I'm not going to persuade her to come home. If she did, shed get sent away to juvy.
From what shes told me, she has to come back after shes 18 (providing she lasts that long) to get her birth certificate and ssn so she can rejoin the world. She doesn't want the people shes staying with to get charged for harboring a runaway. I just want to know how she should approach her grandmother when she comes back because she thinks her g-ma will blow up in her face.
Please no spam about how she was stupid to leave. She doesn't regret it, and from what I hear her life is a lot better. We just wanna know how she should get her papers back. P. S. She can't apply for anything because all she has is an old permit from a year ago. Shes turning 17. She has a year to figure it out, but help would be appreciated.