I see you're from PA, so this is probably a pretty big day for you :)
I think you should talk to your mother. Explain to her that your husband is a HUGE fan and will most likely be yelling and screaming (and maybe even cussing) at the TV. Tell her that as long as she understands that this is his thing, and that she isn't to shush him, she is more than welcome!
Then talk to your husband. Explain that your mother just wants to come over and watch the game. Tell him that you explained the "rules" to her. Hopefully that will smooth things over!
I do think it's kind of crappy that after she was told that you all were spending the day together, she called you and asked.
EDIT: After Mommy B's post, I had to say something....I LOVE football. My entire family LOVES football. If we were Steelers fans, we would be totally ecstatic about them playing in the big game! I totally get J. P's excitement. She's right, unless you are football fans with a team in the Superbowl, you have NO idea the excitement that surrounds the big game.
I really don't understand why Mommy B would basically come on here and bash J. P and her family for enjoying a sport TOGETHER. I think it's awesome that the whole family enjoys it!
PARTY ON J.! :D