What would you do if you were me, go to Philly as planned or stay home in order to celebrate Mothers' Day with your mom? If I were you and my mom said she would be really hurt I would spend the day with my mom. I am saying that as a daughter not as a mom.
As a mom I would not say that to my kids. I also believe that Mother's Day is to over rated. I refuse to go out to a restaurant that day. Of course if my kids want to see me that day that is great and I would do almost anything to make it happen. If they had something else going I would atleast expect a phone call.