Since it was again suggested to make sure that it is legal to keep the snake I will add one more tid bit. I didn't suggest this because 1) I don't feel that it is my responsibility to do so and 2) you came here asking how to help your friend and nothing else, so I did the best that I could. It's like telling someone you don't know who is smoking outside a bar that they should quit because it is bad for their health. It is unwelcomed and usually just upsets people.

As for young colubrids, I find that something the size of a shoebox is just right. A small hide and a water dish along with a heat pad under one side and they will be golden. I was given a hatchling black rat snake as a graduation gift from a friend. Their cats had been playing with it and Peter rescued it thinking that I would be able to take care of it. I did, it ate for me no problem, though I didn't try to feed it for a week, and when it's scars were healed after a few sheds, I let the little guy go in my backyard (I have a natural waterway back there; there was plenty of habitat for it and I'd seen black rats back there before so I knew it was suitable). I did worry somewhat about artificial transfer of genetic material over that distance (40 miles) but not so much that I drove back to where he had been collected from to release him. Best of luck to your friends, whether they keep the little one or decide to release it back from where it came.