Short term

Hello Raquib,
If you are going to join TCS in a month's time, I would strongly advise you to learn something new that can relax you. Like singing, playing an instrument, learning to play badminton or squash or swimming, etc. This will come in handy during high-pressure job in TCS.

Postgraduate courses in securities management, quantitative finance, risk and treasury management and capital markets are all available in National Institute of Securities Markets (NISM).
Similar courses are also dispensed by CCGRT (Mumbai). On the same note, certifications and licenses are also given by BSE and NSE relating to compliances.
You can always go for another undergrad degree or a Masters degree. For instance, a student who has done B.Com enroll for M. Com or LLB, or the ones who have completed LLB enroll for LLM.

There are various certificate courses available that will also match up to the studies done in M. Com:
Certificate in Banking
Certificate in Stock Market
Certificate in Derivatives
Certificate in Income Tax
Certificate in Accounting
Certificate in Micro Finance
Certificate in Investment Banking

Please visit NIBM Global's (National Institute of Business Management) official website for online MBA training and certification. NIBM offers online training and certification for one year MBA, two year MBA and one year EMBA. Please note that NIBM does not offer an MBA degree, but it serves as a study aid. NIBM Global MBA training programs are suitable for working professionals and MBA aspirants.

Yes, there are a lot of short-term courses available for interior designing. Please refer to the link below:
https://goo.gl/vmuZmp

National Institute of Computer Arts, Dadar West, Mumbai offers Short Term Course in Graphic Design but the duration is 3 months course.

Hi,
Since you are preparing for MBA and have an interest in SAP then I would recommend going with SAP Sales and Distribution (SD). To learn SAP you don't need to know any computer programs because the course you will pursue for functional not development.