B.Com

1. Diploma in Insurance & Risk Management (DIRM) [offered by ICAI]
2. Information System Audits (ISA) [offered by ICAI]
3. International Trade Laws & World Trade Organisation (ITL & WTO) [offered by ICAI]
4. Management Accountancy Course (MAC)/ Corporate Management Course (CMC)/ Tax Management Course (TMC) [offered by ICAI]
5. Certificate Course on ADR (Arbitration, Mediation & Conciliation) [offered by ICAI]
6. Certificate Course on Anti Money laundering Laws (Anti- Money Laundering Specialist) [offered by ICAI]
7. Certificate Course on Cooperatives [offered by ICAI]
8. Certificate Course on Not-for-Profit Organizations (NPOs) [offered by ICAI]
9. Certificate Course on Wealth Management and Financial Planning [offered by ICAI]

I am afraid that you cannot join Merchant Navy. Only the Science stream students are eligible for job in Merchant Navy. But since you have completed graduation in commerce, it closes all doors for you.
The candidate who has completed 12th standard with Physics, Chemistry and Maths is eligible for job. He can directly apply for deck cadet job after completing 12th or wait and continue with the studies.
Those who are interested in officer level jobs continue with the studies and pursue either Marine Engineering or Nautical Science course. Unfortunately, commerce students are not eligible.
Indian Navy recruits commerce graduates in Logistics Cadre under Short Service Commission and Permanent Commission both. You need to take an examination called CDS (Combined defense service examination) which is conducted by Union Public Service Commission twice in a year.

GCCBA, Kolkata is quite better than KIIT School of Management. Here are a few reasons:
1.GCCBA established in 1905 and KIIT School of management in 2003 so KIIT is new and GCCBA is old so obviously there are some good things in GCCBA that's why this college is running since a long time.
2.Fee Structure of KIIT University, School of Management is very high as compared to GCCBA Kolkata
3.GCCBA college is having all the world-class facilities for the betterment of the students and KIIT mainly focus on B.Tech.
4.GCCBA college is especially for commerce studies and KIIT gives a degree to almost all the course this mean GCCBA care about this and established especially for theses course and KIIT doesn't think much about these courses because this degree is minor.
GCCBA offers undergraduate and postgraduate courses with specialisation in commerce and business administration.
For more details about GCCBA-Kolkata, check the link provided:
https://www.shiksha.com/college/goenka-college-of-commerce-and-business-administration-gccba-kolkata-b-b-ganguly-street-13132