Hi Asmita, 

Yes, you have to submit a notarised non-judicial bond at the time of your final admission in any government or private medical colleges of West bengal.

The bond is generally of 1lac to more depending upon the institute's norms.

This bond it is mentioned at of you refused to yake admission after all formalities or to  do  the internship during the last year of you mbbs then you would be charged against it and have to pay some penalty for it.

Hope this will be helpful for you . 

For more details and informations you can check out the official sites too . 

Good luck .