Why did Mrs. Van Hopper want to go to New York?

In Monte Carlo, the narrator has been spending more and more time with Maxim. The two are becoming incredibly close, so much so that Maxim insists on the narrator calling him by his first name instead of Mr. de Winter. But the narrator's all-too-brief taste of happiness is suddenly threatened by her boss, Mrs. Van Hopper. She's immediately heading off to New York and wants the narrator, who is after all her paid companion and general dogsbody, to come with her.
Mrs. Van Hopper says that she's going to New York because her daughter Helen is sailing there the following Saturday, and her other daughter Nancy has a threatened appendix. The narrator's none too enthusiastic about the forthcoming trip; she'd much rather spend time with Maxim. Mrs. Van Hopper can't understand her employee's lack of enthusiasm over going to New York. She says that other poor young ladies in the narrator's position would be grateful for such an opportunity for fun and travel.