Hello there! 

Greetings! 

It's mandatory in some institutes to stay in hostel during your engineering program. Actually it totally depends Colleges , sone college tries to get people together from different regions across it's domain and force students to live with unknowns.

For example, I talk about VIT then,  it is not compulsory to opt for a hostel in VIT, Vellore. You can stay outside the college premises in PG/rental apartments. So , it depends on the college. 

Thankyou 

hey yaman singh,In any college there is no rule that living in hostel is compulsory,a hostel is specially for those who takes admission in a college which is very far from their home knowing no person over there, but many people leave hostel due to bad conditions of rooms as well as of mess food.