I am a final year student of B.Com and want to study MBA abroad. What should I do as they need +2+4 students?

Where do you want to study? Not every country requires 16 years of education, so if you have a 3-year Bachelor's degree you may shortlist only those options accepting the kind of profile you have.

You can pursue MBA from Australia or New Zealand with 3 years of Bachelor's degree. There can be other options too, so you need to finalise your destination.