Which course should I pursue after B.Com among MBA and CS?

No one can tell you about this. You have to go by your own interest. Although, both are almost related to working in corporates. MBA will get you a job after 2 years. So, research about it nicely and go by your interest.

You should go for MBA because now a days, there is wide scope of management. You can give CAT, MAT or XAT exam for doing it and can get admission in top 50 business school, if you score well in these exams.

I will suggest that you opt for MBA after B.Com as it will open wider opportunities for you. You must do MBA from top 30 B-Schools for a good management career.