Hi, 

BHU is a very prestigious college and likewise it's cut off is also high. In 2017 opening rank for admission into mbbs was 43 and closing one was 187. For 2018, I couldn't get the exact data but it would have obviously been higher than 2017. So try to score higher grades in exam. Anything less than 630 is nothing for BHU. Higher score is better. 

Good luck!