What can I do if my friend is vomiting and has a sore stomach, can I get her some icecream?

First use medicine. Medicine to stop vomiting is first thing you need to do. If there is no more nausea/vomiting then something soothing for the stomach would help. Ice cream is pretty rich to digest, low fat milk or broth may be better to start with. An antacid might also help for an acidic stomach in case she has heartburn.