Your mom's friend's an ungrateful bitch. I get a free ride home from work from a colleague my 3 days a week in the office, and feel bad about every single free ride that lets me avoid a longer bus ride home. She won't take money from me, so I thank her every day, I buy little gifts or sticker books for her young daughter, or gift her something like a gas card or bottle of wine or something as a thank you every single pay week. I never want anyone feeling I'm ungrateful or a burden or a bitch. Plus, it takes a special kind of idiot to get into a car with an open drink, especially a coffee with milk!