Need some help about my mom?

Now it’s 23:30 and mom isn’t home. Later back in the evening she told me that dad and her were going to meet up for some beer. At like 21:50 or something, dad came home, he had left her at a bar. She wanted to take the 11:00 bus but she missed it. Now she calls me and tells me that she’s sleeping at her friend’s house. I became mad*angry* because I hate it when she drinks. My mom is thin and sometimes people think we are sister and stuff and so that just kills me especially when I see her drinking like that. I think it isn’t good for her healthy. Mom and dad had a fight at the bar so he left her:/ – he’s my step-dad but I just call him dad-
Then when I was talking to mom on the phone she doesn’t sound clear and stuff. I became more frustrated and she tells me to take care of her, I said “mom how can I take care of you when you are so far from home?” she’s like 45 minutes from home or something….

p.s she isn’t an alcoholic, she just drinks sometimes.
and sorry that it’s maybe too long:/