Short term

There are various short term courses and diploma courses you can opt for after your B.Tech. It can be a certificate course in embedded technology, VLSI, robotics, ethical hacking, protocol testing, machine designing etc. or a diploma course in any specific domain.
Such courses are generally job oriented and serve as a bridge between what you know and what the industry expects you to know in order to absorb you into their organization.

Hi,
Tally is a short term course, which you can do before MBA or PGDM. The duration of course will be tailored as per your interest. If you want to learn only the basics of Tally then it will take only 1 or 2 months to complete and if you want to learn complete Tally, then it is for 6 months.

Hi,
You can do it. Go for to MAAC, Arena, Framebox, etc.
These are the best in providing animation and VFX courses. Go and council the courses as per your budget and time.

Dear Mrudul,
You have already answered your own question. You can pursue graphic design course from Pune. But a 3-4 months course will not help you learn a lot. You will at least have to spend six months to master your skills.

You can go for some computer oriented courses like, M.Sc (IT).

You should probably use your skills what you have acquired in MBA for good corporate job and sharpen them, you can then opt for some short term courses on Digital marketing and Businesses Analytics from Coursera.