I'm with Irulan on both her points. If your classmate continues to press you for a ride and you feel like a broken record in coming up with excuses, then I'd just tell her the truth. "You've made me run late so I'm not going to give you any other rides." Sounds harsh, I realize, but it may be something you need to say and she needs to hear.
But I also agree with Irulan that her others issues aren't your problem. I wouldn't talk to her school counselor about them. In fact, I'd be shocked if a school counselor would even talk to one student about another student's "problems" unless they were a threat to themselves or others. I'd otherwise just try to distance yourself as best you can. How much longer in your program do you have?
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher