Well, she was a no-show! I have come to the conclusion that this is an epic parenting fail, and the mom is a wimp. Wimpy Mom could have prepared the girl--dancing at home, talking about what was fun about the class and why dancing is a good form of exercise, and reminding her child every day that they were going to try the class again. Notice that I am not advocating forcing a child to participate in an activity she clearly dislikes, merely giving it enough of a chance to see if she will do it.
What would you do if you took your child to an activity and he/she only participated under duress? Make him/her continue, or let him/her off the hook?