Should i tell his mom to save him?

STOP TALKING TO HIM! HE IS A LOSER, yes you can still care about him but when a person does drugs the only thing they are gonna care about is the drug, they will manipulate other people , use them, even steal and lie. is that worth all your heart aches . NO... just let him be , consider the money gone.. pray that he gets help. I bet his mother already knows, if he sees her or talks to her, bring it up to her and just be nice about it, you could though start a bigger problem. best of luck to you