Mom coming to visit me in China, but not staying in a hotel when we're in Dalian.

She is coming to visit me in my town of Dalian for three days, and then we shall be in Beijing for four days. We are getting a hotel in Beijing, but when she is in Dalian, we are planning to stay in my friend's apartment. When she goes to apply for her visa, what does she need to say? It's not my apartment (since my dorm doesn't allow for overnight guests), but my friend's. Does she need any documentation?