This girl got it right.
My beloved R, who is no angel, was allegedly part of a group that acted disrespectfully during a classmate's bat mitzvah. I'm told the girl knows little of the gang's what-were-they-thinking behavior but her mother's in the loop--and understandably disgusted. What do you put in a thank you note if the standard "I'm glad you could celebrate with me" is a lie?
How about this: "Thank you for the money. It will go towards my future." Honest, and sort of adorable.
Good for her and her mother for taking the high road and sending a thank you note.