Depending on the rules of the college it may or may not be compulsory.

It is adviced to stay at the hostel. It gives the right study environment .You will be doing a lot of group studies and hostel will help you with that. Like saving transport time , library facilities, you can choose your own time to study as well. It's not mandatory for most of the medical colleges to stay at hostel. So directly contact to college to get detailed information regarding it.