Turn it into the cops, and if you're lucky then no one will claim it within the standard amount of holding time, after which it will be yours and you'll have a clear conscience. If you turn it in to the cops, here are the possible outcomes:
A) A person in need reclaims it and acts grateful to you for basically saving their life.
B) A reasonably well off person claims it and gives you a very small reward which you get to spend and also feel good about morally.
C) A reasonably well off person claims it and gives you no reward.
D) No one claims the money and after a waiting period you get all the money and get to spend it with a clear conscience.
E) The cops "claim" it is drug money and keep it for themselves.