What can I do for my mom?

My mom has been dating this guy for about three years and he’s lived with us on and off for two years. He doesn’t keep a job for more than two months. He doesn’t co tribute to bills. She buys him beer and cigs with her hard earned money. I’m 24 I live at home because that’s what’s best for everyone involved. He could at least get some food stamps but SHE asked me to help him get food stamps....I don’t need or want to help a 45 year old man do anything except find the door....he’s nice but this is unacceptable. She even complains that he is not affectionate towards her. I mean he doesn’t even clean. He barely knows how to cooks so we try to avoid that happening. And me and my brothers have seen him using dating sites/porn on a regular basis...all he does is sit around drink beer and watch tv/phone. She’s not happy. I think she’s just with him for comfort. But how can that be comfort. I’m happy single and I’ve been in her shoes before and never again. I want to continue to help out with food and bills but him being there really doesn’t add up. Am I wrong? We’ve talked to my mom and she just gets quiet and avoids it she confronts him but nothing has changed it’s been 3 years...he’s not going to change! He’s nice but of course he would be when he is living for free...