You can go for msc mathematics or mba, choice is yours.Looking  into current scenario i will suggest you to do mba.

I would advise you to choose best University on the basis of University ranking, placements, infrastructure, faculties etc.

List of some of the Top and best private   colleges in India are the following

LNM Institute of Information Technology, Jaipur

Vellore Institute of Technology, vellore

Manipal Institute of Technology

SRM Institute of Science and Technology, Chennai

Dayanand Sagar college of engineering, Bangalore

Geeta University, Panipat,

RV college of engineering, Bangalore

BMS college of engineering, Bangalore

On completion of your graduation from a BSc Mathematics degree, you can pursue courses like MCA, M.Sc IT or M.Sc in Mathematics, Actuarial Science, Statistics. You can do B.Ed. There's a lot of courses available to you after bsc mathematics. You can also go for M.Sc + PhD integrated course. If you are interested in Management line, then you can do MBA. There are a range of courses available to you when you complete your graduation in Mathematics. If you are interested in Teaching profession, then after completing MSc, you can appear for NET.  Otherwise, you can start preparing for Banking Exams or Civil services. Its upto you which one to choose. You need to work on your point of interest and passion.