I don't want to go to my mom's friend's college graduation
Why don't you want to go to the graduation?
I want to go hang out with my friends instead.
It's fine that you don't want to spend your time on someone you're not close to. Your mom's friend isn't exactly your friend, so you should hang out with your friends like you want to.
But mom will get mad at me if I don't go, and I don't want that to happen.
Talk to your mom about it and find out why she thinks it's important for you to go; you should keep her wishes in mind. If she still really wants you to go then make plans with your friends for afterwards.