MAT

It is not a good decision to go for MBA without entrance or to buy the education through management quota. As thing which comes easily is not worthy, make yourself worthy to get a secured job otherwise you may have just degree and uncertain job with 100% placement show off. Try sept MAT and it is not tough or need so much hard work to score well just be little tricky.
Join LinkedIn / Quora to have alumni chat to get the unbiased truth of after placement stability.

You can go for it. But with your score, I think you will not be able to get admission.
https://www.shiksha.com/mba/course/post-graduate-diploma-in-management-itm-business-school-navi-mumbai-itm-160351

Yes, you can get admission.

No, you need to score minimum of 60 percentage in graduation and you need to score around 700 to 780 in mat exams then you could get into good b school. There are some college which can give you admission in MBA such as Amity University Uttar Pradesh, Noida. JIMS, Rohini, AIMS Bangalore, ISBR, Bangalore, but after two years, you will find job, but return on investment is too low. Choice is yours.

With this score, you will not be able to get admission in any MBA college. You should give the exams again.

Hello Rahul,
There are no reputed B-schools in Kolkata which accepting scores of MAT exam:
https://www.shiksha.com/mba/colleges/mba-colleges-accepting-mat-kolkata Visit this link to know about the other colleges accepting MAT scores.

If you want to take admission into the top 20-25 B-schools, you need to given exams like CAT, CMAT, SNAP, XAT, etc and not ATMA and MAT(as the no. of good colleges are very less). As long as you have at least 50% marks in graduation, you're eligible to appear for all of these exams. https://www.shiksha.com/mba/articles/20-mba-entrance-exams-you-can-take-this-year-blogId-11473 Kindly visit this link for more information about these exams.

CAT and XAT are toughest exam. You would need more preparation for these exams.

No, I don't think there is any chance with this score.