Desperate for help

First of all, I’m sorry if this is kind of long but I need some help ladies.. my mom is so depressed. She had three daughters, myself (24), my middle sister (21), and my little sister (17). She and my dad divorced when I was 10 just because they weren’t happy. No bad blood or anything. I’ve been moved out now for 7 years and have two kids of my own. My middle sister has been moved out for about 3 years now and her bf now lives with her. My little sister just recently started dating this guy about 6 months ago and he lives a couple hours away so she’s been trying to split her time between there and here but she’s been spending a lot more time there since the pandemic trying to stay isolated with him. So my mom now has an “empty nest”, and is extremely single she doesn’t even want a boyfriend. She is getting so down on herself because she’s so lonely, she thinks we’re not around because we don’t love her etc. she’s getting tied up on all the bad moments and everything she regrets and overthinking everything cause she’s alone and bored. She’s drinking almost every night after work. She says she lives to work and pay bills and feels like she just wants to sleep forever. What can I do to help her? She’s got so much going on rite now, her car is fucked and she just spent $2k trying to get it fixed and it’s still causing issues, my youngest sister just left again today, she took time off to spend with me and my kids but my sil who lives downstairs from me had her husband come visit (from Florida) so obvs we all had to quarantine and that really upset her, she misses having little kids and I get it but I also don’t know how to make her feel any better. Any advice is soooo appreciated. 😔

I should add that her father committed suicide when she was two years old by shooting himself in their house, and she was battling cancer at the time. And she’s talking about that too.