I was just wondering if you got accepted before you graduate from your final year of undergrad, does that mean the acceptance is conditional? aka they can change their mind if they see a bad mark in your last year even they've already seen all your pre-req course marks"?

I think it is conditional that you finish the degree in good standing. I don't know what would really happen if you fail classes or get Ds.

The only conditions I've seen are finishing the required course load and graduating. I don't think they can decide to reject you because you get a C+ in a class or anything like that.