MCC - Madras Christian College

It should be around INR. 2 Lacs for all 3 years put together.

https://www.mcc.edu.in/
hope it helps.

Yes, you are eligible for it, MCC says "graduate degree in any discipline with at least 50% marks."
The selection process is Meri Based.

If you have online results then you can take a copy of it and can submit without submitting the marksheets for getting admission in M.Sc Mathematics. Later you can submit all the semester marksheets once you get them all. Else just inform that you didn't get the mark sheets and take admission based on those results of the first three semesters.

for this you have to go to the respective website and apply for the college and also look out for the cutoff

Yes, of course, you can. You meet the eligibility criteria.