Urgent help needed please!!!!!

Ok so basically the guy I'm dating invited me for dinner with his family, now I can't go because I'm having dinner with my family. So his mom said for him to tell me that she can pick me up and come back for a drink to their house and stay in his brothers room and she'll take us to school in the morning.

Now don't get me wrong it's so nice of his mom to do that, but now it's awkward for me cus I'd rather just not do that because it's just really complicated like I'd have to bring all my school stuff to dinner and then I wouldn't get back to his house until late then I'd just be staying until the next morning when we have school and I wouldn't be able to get ready properly and stuff likeeeee it's so nice of them but it's just really complicated.

The thing is I don't want his mom to think I'm being rude or flaking him off but idk what to do now 🤔🤔🤔😩😩😩

ANY HELP LADIES?! WHAT EXCUSE CAN I GIVE WITHOUT HIS MOM NOT LIKING ME?!!!!