Does senior year grade matter a lot??

So, I got into Northeastern, and I kinda bombed my AP Science class, I got a C. Would the college reject me if I get one C while I already have a C in my junior year and they still accepted me?

How much did it affect your GPA by? If your grades were otherwise comparable, then you probably won’t get rescinded. Keep your grades up as much as you can.

No the university will not rescind your admission. I see no reason why a single C will impact your acceptance so riotously.