It's very nice of her to help you. I'm sure she wants you to feel comfortable so that if you enjoy it, you'll want to compete again! I don't think that it is necessary to give a gift, but certainly it would be appreciated. When my pro's wife has gone out of her way to help me, I've given her a gift certificate towards a manicure, or to the local coffee shop. It's small, but just a token to show how much I appreciated her help. She seemed to like that.
Good luck on your competition, and enjoy!