Hi Billy!
Most sororities realize that women are really nervous during rush. However, everyone deals w/ it in different ways. Some girls become chatterboxes while others can barely say their name.
She should know it's okay to tell the girls "I'm so nervous, I hope you don't think I'm not interested if I don't talk a lot." Or something along that line.
It's actually the job of the members to get her to relax and open up. She should realize that every member she's talks to has been in her shoes. We all go through some type of rush. The members can relate to her!
p.s. It ususally helps if she thinks of rush as a one way decision. It can make her feel more powerful if she just thinks that all the sororities are competing to get her to join their house. Of course in reality it's a mutual decision.