What should I do after completing B.Sc for a bright future?

For bright future after B.Sc, you should pursue M.Sc through JRF and from a good college. Then, later pursue Ph.D from a good University. It would take nearly 6 years to complete, but you can then be able to apply for Junior Researcher in many departments or teach as a professor in a college.

It totally depends on your graduation subjects but it's better if you can pursue master or crack any civil services exam otherwise now days graduates are earning 12k per month. The choice is yours.