Every course or stream like Financial Management, Marketing Management, Operations Management, Human Resource Management, IT Management etc. is offered to every student getting admission in any of the b-school all on your choice irrespective of which branch or subject you studied during your 12th standard and graduation.

Anshuman, I personally suggest you to not to worry about opting any branch right now because it totally depends on your interest. Your graduation stream doesn't matter at all for the branch you want to opt while pursuing MBA degree.

In most of the top reputed colleges like IIMs and other private colleges in the first year, you are taught subjects from all the streams. This will give you enough time to figure out in which stream you are more comfortable and in which stream you actually want to make your own career.

Then in the second year, you are given the option to choose two streams one as Major and other as minor so that you will be studying all the subjects related to that stream only. Although in IIMs where there is General Management degree; there is no major-minor so you are allowed to choose all the subjects for the second year from any streams. At that time you can take more subjects from the stream which you like. Say if you like Marketing and Operations then you can pick most of the subjects from these streams to study in the second year.