Arriving at a place days after holiday get togethers are finished.

I am upset. Yes, I love having family over for thanksgiving, but after my visitors left, my mom's friend who was going back and forth about coming just decides to come two days later. This was literary when my visitors are on their way out the door. She complains that the food she asked me for was not looking good,and starts conversing with me. Am I wrong for being internally upset. I would like to have peace, quiet, and time to study for my exams, which is next week mind you. However she pops in out of nowhere like thanksgiving is supposed to be on hold for her. I don't know what to do. I told my mom to try to discourage her from coming, because I knew that it would interfere with me getting things done.Regardless my mom ignored my request. Do you think it is wrong for me to be upset, or is it being selfish? I don't want to be unfair.