It takes a few sleepless nights of musing to come to an answer.
Elsa doesn't want strangers in her home.
While that may be true, she also gets the feeling that it's not the entire truth. She doesn't even get a chance to talk to Anna about it - about anything going on - because she's always out of the house. School is finishing up for the year and she has a number of exams and assignments due. If she's at home, she's usually sleeping or studying.
But… it doesn't really feel like home nowadays.