Awe sweetie, I am so sorry about this situation and about your hearing. I hope you get good news today from the doctor.
There are a couple of kids in my DD's class who don't get to have a parent at events. There is always an extra parent that adopts them in and they always have a blast. So, don't beat yourself up about this. She will have a great time today and tonight too!
Tight Hugs, Happy Halloween!