I hope this helps you, because I'm speaking from experience as the friend.
When I was 16, my mom and I left my dad because he was being physically abusive to her...which I have to say...was about time. Anyway, I moved with her here to AZ where she moved jobs constantly, and we moved apartments and rooms and houses. Because of this, I was missing school, and loosing interest in school because I wanted to find work to help our ‘family’ but I was too young and not in school so nobody would hire me (thankfully) and I also I didn’t want to go to school to have people ask me “Why weren’t you in school.” Because then I’d have to tell them. Or lie…and I didn’t want to do that. I was falling through the cracks, fast, and nobody, not even my school counselor could help me. There are only so many encouraging words she could say. She probably could have called CPS but I don't think she did because they never came. I ended up running away from home to stay with a friend and that didn't really work out, so I stayed with another friend and so on... The boy I was dating at the time told his mom about my situation and she offered to become my legal guardian. She let me live at their house and went to court to get guardianship (I honestly don't know how she did it) but I went to see my mom and I asked her to please give up her parental rights so I could be successful because I know that is what she really wanted for me. We talked for a couple of hours and I convinced her to sign the papers. It was the hardest thing I ever done, but it was the first time my mom really did what was best for me. I had structure and guidance, which was a complete shell shock, but I also got my first job and started saving money to go to College and started learning how to do things that I never really learned how to do. Talk to her about the possibility of becoming her guardian and see what she says. Also, when I was 16 I couldn't emancipate because it wasn't something they did here. They might now, but I know they didn’t then.
I went to school at an alternative high school which allowed me to earn the credits that I was behind on (which was almost half of what I needed to graduate) and I finished all my classes and earned my credits in time to graduate with my class in 2000. I think I’ve done pretty good for what I went through and I think your daughters friend will do the same. Maybe it’s something that you could look into for her. Also, I don’t know what they’re like now, but I went to a charter school for 6 months to earn some credits, and basically the credits didn’t transfer so I did all that work for nothing. Things have probably changed since 9 years ago, but still, do the research. Also, if she’s a junior, then she could probably take summer school and take extra classes during school time to make up her credits. I know most seniors get half days because they’ve finished all their credits and don’t need the extra classes. As long as it isn’t a course that needs to be finished before going on to the more advanced version (like Spanish I to Spanish II) then I don’t think 1.5 is too many to make up.
My guardian literally rescued me from a really bad situation. I won’t say it wasn’t strange, because at times I felt like an outsider, but I think that’s part of realizing who you are and trying to figure out where you belong in life. Just be positive and supportive. I still talk to my guardian regularly, and I talk to my mom too. And my ex boyfriend is one of my best friends, and if it weren’t for him and his family, I don’t know where I’d be. Once she sees that someone values her, she’ll value herself and start aspiring for her future.
Good luck in whatever you decide to do.