I think my mom has depression... what should I do?

My mom is 54 and she struggled with her mental health when she was young and never got proper support. She’s very moody in general and her mood changes in a split second. I have a very weird relationship with my mother because she is difficult to deal with and often hurtful to my feelings, but I’m worried about her. She has been very off lately, cries a lot, says that she is alone and has no real friends. She says none of her friends ever invite her to go out and she doesn’t want to do things anymore with her friends but she used to be a very social person... She has also been extremely hateful to my dad lately and my dad is an angel but my mom has been using him as a punching bag lately(metaphorically). I’m worried about her because of her history with mental health. What should I do???

Also since I’m anonymous, I’d like to thank everyone in advance for your responses💖💖💖💖