B.Com

It is good to see your interest towards the higher education. MBA and M.Com both are the good master degree courses. The scope and opportunities of both course are good in their own sectors.
Basically, going for any course is depend upon ones interest as well as liking. Personal liking as well as interest varies from person to person.
For being eligible in the MBA course it is must to have a bachelor degree in any stream from a recognized university with minimum 50% marks in the aggregate.
For M.Com course, it is necessary to have a bachelor degree in commerce stream from a recognized university. If you are interested in the business and administration sector and want to develop your career in management area then it will be great decision to go for the MBA course as your master degree course.
But if you think that you are not interested in this area then you can simply continue your study in the same area by opting the M.Com course.
Since the decision is depend upon you. Your decision may change your life. So think very carefully before any decision.

That depend on the career you wish to pursue. If you aspire to become a CS. The company secretary is responsible for the efficient administration of a company, particularly with regard to ensuring compliance with statutory and regulatory requirements and for ensuring that decisions of the board of directors are implemented.
1. CA is a vital link between the company and its Board of Directors, shareholders, government and regulatory authorities.
2. A CS ensures that Board procedures are both followed and regularly reviewed and provides guidance to Chairman and the Directors on their responsibilities under various laws.
3. CS Commands high position in the value chain and acts as conscience seeker of the company.
If this is what you wish for yourself than you can pursue CS else their many option after B.com such as M.Com, MBA, etc.