Just as I suspected. Unbelievable that she didn't call or come back but nothing you can do. You offered her some help. I expect she will try again but you have to be ready for it and offer what you are comfortable with. Some advice, a meal - whatever. But don't be taken advantage of.
I have a friend who I've known my entire life. But she is up and down. Good for a few days, gone for a few days. Each time I see her I fear it will be the last but I can't enable her. She has to sort it out for herself and stop drinking.