Hello dear, 

Some of very good coaching institutes are mentioned here, have a look: 

1) neha's institute of mathematics bsc, chandigarh

2) IIT JAM maths coaching in chandigarh

3) maths vidhya institute, chandigarh

4) info maths

5) infotmaths

6) RN classes

All the best!

BHU Entrance is not as tough that you need to take the coaching, if you are well prepared with your 12th syllabus then it will help you to crack the exam, Go through with the previous year papers to take an Idea about the level of the questions, Do practise as much you can.

Good Luck!