To begin with, FMS does not take into account your graduation grades when making final hiring decisions or shortlisting candidates. Only your 10th and 12th-grade marks are taken into account, and they are only worth 5 points each. As a result, the grades you received in previous exams will have little bearing on you.
When it comes to a year back, it's becoming increasingly difficult to explain this. Any B-School expects you to have at least average grades on your previous exams.
Whatever is done is done, and it is recommended that you do not focus solely on one college, but rather keep your options open, and then prepare well for the CAT, because if you do not perform well in the CAT, all of these discussions are futile. It's better to think about all of this after the CAT because even if you don't get calls from these colleges, you'll have done your best and will be happy in whatever B-School you choose. So, first and foremost, prepare thoroughly for the CAT.