I would help - the daughter asked you to help HER not the ex. Then again I don't have an ex, so I have no real world experience on how I would feel if I did have one. I think I would want to focus on the fact that my daughter wanted my help, and that it would be setting a good example in graciousness to help her. Of course, if you really can't bring yourself to do it maybe you have a quilty friend that could help her? Good luck either way.
I don't mean to play Devil's Advocate here, but imagine how the Bride will feel, sleeping under a quilt made possibly through the help of HIS ex??
Just a thought!