What should I tell her?

So I live in my dorm which is about 45min from the where my parents live.

My mom asked me if I could come home Friday night to stay with my sister (who is 16) while my parents go stay at a lodge for the night. Normally I'd have no problem with letting them get a way for a bit, but I just feel like it's unnecessary.

For one, she's 16, and I was watching her when she was 12 when I was her age. Secondly, my grandparents live next door and we've stayed many nights there while the parents went elsewhere. When I suggested sending my sister over to their house she said, "can't you just come home? It's not too much to ask."

The biggest issue is I have a lot of class work that requires internet access, and there is no wifi or anything at the house. I don't mind going, it's just there's a lot I need to do this week and I can't get all of it done before Friday.

I feel like my mom just wants me home because she has not taken me being in college well these past couple years. I get it, I'm her daughter and such, but it gets overwhelming.

What should I say?