If your friend has just been raped, she may need your encouragement and support to get through the next few days. Encourage her to seek out a trained professional for counseling. There are many long-term effects of such a traumatic experience, and she will need help sorting them all out. Offer to stay with her.
Rape victims are often afraid to be alone after such a frightening ordeal.
Accompany her to the hospital if she needs to go. Suggest she call the police and report the incident. Respect her decision if she chooses to keep this to herself. This is a very personal choice and you can't make it for her. Be a good listener.