If she's your best friend, then I would keep reaching out to her. It sounds like she feels you don't really care. I'm not saying she has grounds to feel that way. After all, she said she was okay to drive. But she may be in an insecure, somewhat needy frame of mind. You can choose to be the bigger person and send a heartfelt message of concern.

If she persists in not responding, then you've done what you could, and it may be time to leave the ball in her court.