Hello Misti,
Yes, there is an entrance examination for admission in MBA in BHU, Varanasi. You have to appear in PET for admission in any postgraduate program in BHU. Once you qualify it, you will be called for further process like GD, PI written test, Personality Test.
Then you can secure admission in BHU. There is 30-60 seats in every branch of MBA.
Good Luck