Anorexia...what to say??

I have a niece suffering from anorexia. She's just been diagnosed in the past few weeks after two life threatening hospitalisations and is entering a clinic for full time treatment tomorrow. I'm going to travel down to see her for the day, twice a week and I'd love to be able to support her the best way I can.
Is there any advice someone could give me on what to say to her? Any tips on how she may be thinking? I really want to do this right. I'm so worried. Thank you