I don't think your sister's dream and the incident you experienced are necessarily related. Your sister dreamed about a friend being raped; in real life, your house, not your sister's friend's, was broken into, and nobody was raped.

Your sister's dream about rape could symbolize her anxiety about something in life, or a feeling that she doesn't have control over something.

It's also possible that your sister noticed something about your home which made her feel that it could be unsafe, and that made her feel anxious, which brought on the rape dream. So the dream didn't directly predict the event, but your sister did notice the possibility that a break-in could happen.

In regard to something similar happening again--this isn't dream related, but I have heard that in real life, once your house has been robbed, you are more likely to be a target again, so you just take whatever precautions you can, such as installing a burglar alarm, to keep yourself safe.