Sir, I have applied for masters programs in BHU and stated my self as a candidate seeking reservation under EWS category.
You will get both general rank and EWS category rank separately.
If you have received a call letter from Banaras Hindu University and your rank is good enough then you must attend the counselling because your name will be called both under then unreserved category and also under the EWS category. Not producing the certificate should not be much big of a problem.