mental health agencies, Dept of Work Force, or other places like that. This kid needs more action and less talk. He's acting like that to get what he wants and the sooner mom gets control the better.
Immediate, related consequences handed out with as little emotion as possible (sad you made that choice and sucks to live w/ the results), and backing up everything you say with action. It's not easy but the good news is that he's young so the corrections can be made but it will start with her learning how to respond.