Deafness itself is not horrible. Having something taken away from you is. She had her hearing all the way up to her teen years and now it is taken from her in a sense. So yes, it is horrible for her. Since she has lost something she once had.
Blindness is not a horrible thing. If you lost it all at once how would you feel??
Some people offered me thoughts and prayers with lots of "I'm sorry" when they found out I have Usher Syndrome. Like it is a horrible disease that I will die from. Which in fact it is not. I will make adjustments and work thought it. Right now your friends daughter just need support. I would offer her resources that may help her adjust and learn about deafness.