I hope you texted your mother letting her know you failed the test because she removed your internet. You probably didn't, but i'd still do it just to make a point to her not to mess with things she doesn't know.

Meh. You should have just told your mom about it instead of letting her find out on her own. this could have easily been avoided. As far as what to do now goes, go a mile in almost any direction and you will probably find a McDonald's. Get something off the dollar menu and sit and eat it while you take your test. Doesn't seem like such a major problem, just a minor inconvenience that could have been avoided.

Library, friend, or neighbors house.

I feel sorry for you, OP. I probably wouldn't be able to last 1 day without Internet, exam or no exam, haha.

Worst case you go to a like McDonald's with wifi and take it there

Public library?

I assume you've sent this from your phone, then you can just connect it to your PC and turn USB tethering on, then you'll be using your phone's data on the PC. I only know that's what it's called for Android, but I assume iPhones have an option like this too (probably with the same name)

go buy another router, and then when you're done take it back, or put it away in case this ever happens again.

Public libraries have free wifi, and some have study rooms you can rent so you can take your exam free of noise or distractions.

Ask to borrow a family member's or friend's computer