For getting into any government medical college, you should have a score of 550+ in NEET. Also, the competition for those seats in government colleges is very very high, so yes 550+ is the minimum requirement. But depending upon your category it may be variable. If you belong to SC/ST it should be 450+ or else it is 550+. 

Here's a list of all government medical colleges in India

www.medicine.careers360.com/colleges/list-of-government-medical-colleges-in-india-accepting-neet-ug