A: It depends on why she asked you: Because she's interested in you romantically, or because she's planning on dumping pig's blood on your head once you are ironically named Prom King?
You should also take into consideration whether or not you were sitting behind a table when she asked you. If you were, she might not know that you are confined to a wheelchair. If you weren't behind the desk, she might have been mocking you. Did she snicker when she asked you, then claim to be thinking about something funny? Sometimes they do that.
No?
So she knows you were in a wheelchair, she wasn't mocking you, and she wants to go to the dance with you?
This girl doesn't happen to wear dark glasses and carry a cane does she?
No?
Wow.
Son, I suggest you marry this girl. You might never get another chance like this. At the very least go to the dance with her. You'll have fun. And I need you out of the house on Friday anyway. I'm having a few of my ... friends over and you creep them out. And when they're creeped out, they don't tip. And Mommy has boob payments.