Wow.
This is a great question, I’m kind of ashamed I don’t know the answer. I’ve paid a lot more attention to disability-friendliness and accessibility at conventions lately (sadly, it doesn’t seem to be a priority at many, yet). But I’m not aware of specific programs for the hearing impaired.
A lot of the anime shown at cons is subtitled, I imagine she would be okay there, I don’t think cosplay needs to be heard to be enjoyed…It SEEMS like most things, except maybe panels, would have easy access for your friend, but I don’t want to speak for people who are hearing impaired.
So I’ll throw it out…anyone out there with experience relating to this question?