I am having marketing as my Major and finance as minor.
my graduation is Bsc physics (hons)
but I am no more a science student now.
i am having placement in BERGER PAINTS, icici life insurance and 2 more companies.
but I am having urge to go for UPSC exams. how to go ,where to go is uncertain for me?

You have interest in UPSC. And you have done MBA in marketing. That is great. Because you have a backup and a path to move ahead in your mind. But this is a good option. But you should remember these are 2 different mindsets and there is a major difference when seeking success. The first that is MBA will give you personal growth and the other requires energy for growth of others.
Being an MBA you would want to be an entrepreneur, brand builders, comunnicators globally.
Being a civil servant you will have to work for the benefit of others and you can be working in remote areas etc. You have to deceide it by self. What field you are looking for. Both fields are different but incase you are looking for short term sucess then you can find it after MBA probably. Good Luck.