Gut, go with your gut feelings! Just the fact that you feel you want to help her, to me says alot. Everything happens for a reason, you bumping into her at the gas station was meant to be.
God forbid something happens, she gets mixed up in the wrong crowd again, or whatever, you'd never forgive yourself. People come into our lives for a reason, I believe that. She will be ever so grateful, and you will have a great sense of satisfaction.