My family and I have had multiple negative experiences with selling things to friends and family, including a vehicle we sold to a relative that then exploded on the freeway. Even when it's been mutually agreed upon that the item is being sold as-is, when the person knows you and something breaks, they inevitably come back and either want you to fix it or blame you for it. I'd be concerned...especially since it sounds like the bike doesn't fit her. And the helmet thing...oh my. I'm kinda speechless on that one.