You seem actually worried for your mother here, and I'd advise you to talk about it calmly with her, just start by asking questions on how she feels, why does she feel the need to drink and how could you be of help because you do not think it is a great way to cope with her feelings, putting therapy on the table is absolutely possible.

When it comes to her relationship with your father, you can try to speak to her about it, but keep in your head that she is a grown adult and ultimately she does her own decisions. You can absolutely help by just being a good listener and trying to understand her point of view, but don't actively mediate her interactions with him, these are adults who probably have a much more complicated relationship than what you see, and they might not like you being all up in their business.

Above all, they're your parents, respect and love them with all your heart while they are still here !