You've reached that difficult stage as parents where learning to let go a bit so they can grow and develop into independent adults is difficult to do but must be done. Its usually worse for the mothers letting go. As for what to do, I would suggest you thank her for asking for permission, explain why her mother might be worried about her going and tell her you will talk to her mother and let her know your (joint) decision - to avoid the trick of using one of you against the other. But then try to find out what her mothers fears are, put in place maybe one or two light rules, like picking her up when its finished, to satisfy her mother but then persuade her that she is going to fly the nest at some point in the next few years and she has to be encouraged to learn to fly solo in a supportive and caring environment which she won't do locked up at home.
But I'll tell you what her mother is going through is nothing compared to what you will go through when she brings her first boyfriend home and you realise that his intentions towards your daughter are the same as yours were towards girls when you were that age.
(from the Dad of two well adjusted and independent daughters now beyond their teens)
But I'll tell you what her mother is going through is nothing compared to what you will go through when she brings her first boyfriend home and you realise that his intentions towards your daughter are the same as yours were towards girls when you were that age.

(from the Dad of two well adjusted and independent daughters now beyond their teens)

