whole selling issue. sellers are wanting to backout sign contract

[Dee Brock]

So I signed a seller up on an assignment contract and 2 weeks later they called and said they changed their mind and do not want to sell. What legal options do I have? What would prevent them from cancelling with me and just selling to someone else for more money? I also fronted them 1k to help with their moving expenses which they have told me they will pay me back monthly. Any advice. I don't want to beat these people down because life is extremely hard. but I also want to learn the right way and hold people accountable.