Thats horrid news, from experience there is a few things to avoid saying, but nothing to actually say. My advice would be to be there for her friend and the family, don't just offer your support and wait to be asked, help out and get involved.
I know it sounds stupid but also don't forget, what hurt us the most was a few months down the line we were still very much grieving yet everyone else had moved on with their lives, which is fine, although it hurt when some didn't take moments out of their life to mention it or show some support anymore, those that did have made a mark with us and will never be forgotten.
Once again, tragic news... so sorry for the family!