Well then, they should have changed the date or otherwise re-arranged their schedule. Just because they had other things to do earlier in the evening, does not give them the right to violate good manners and knock on people's doors at an unacceptable hour.
They asked their parents if it was OK to run out cookies, and they said yes.
Did the parents know they were taking the cookies to strangers? Did the parents know their children's planned method of delivery? If so, then shame on the parents for not teaching their children better manners and judgment.
They started this cookie delivery at 9:00 yet didn't arrive at this woman's house until 10:30...