If Rei explicitly has no place to go and no plans for her future, Greed's actually a pretty practical character if not in impractical ways. Rei might protest to some of his suggestions on how to make a living, but he'd probably attempt to help her find employment she could live with or some means to get by while going to school if she still intends to do that, or helping her decide what she wants to do and how to practically get about to doing it. He'll probably be so bad at it that anyone watching will step in and help Rei in his stead, but, if you're interested in playing with the real life post-tang outside of psychological/characters issues, we could try to work in that kind of angle, too.