What to do about a stubborn teenage boy?

I have a friend who’s going through a difficult time with her 13 year old brother.Her mother is out of town and her father has not been around since he left the family when they were very young. The mother has medical conditions that she is dealing with and can’t be burdened with anything because it could have severe consequences for her health. In the meantime, the brother is getting expelled from school, getting into smoking marijuana and hanging around bad people. He has ADD and ADHD and emotional problems and my friend has no one to talk to but me and I honestly don’t know what to tell her since I have never been in her position. The school does not understand that sending him home and suspending him for a couple days is just an award for his bad behavior? My friend does not know what to do about him and is juggling work, school and now these problems. I can see that she’s at the end of her patience and is getting extremely stressed about this situation as anyone would be if they were in her shoes. I guess my question to you is how do we make him stop getting into trouble? He’s currently enrolled in a special program at his school but things are getting worse every day. Today, he got suspended for being in possession of marijuana when he for sure got it at school, since that is the only place we let him go unsupervised. He also now has a court date and it is getting ridiculous, especially for his age. When he got caught, he showed no sign of remorse and does not feel sorry whatsoever. Didn’t shed a tear or said anthything remotely close to “sorry”. Any type of advice is helpful…