Hello Sanjeev,
Their are a total of 1,122 MBBS seats in Bihar colleges, including private colleges.
Here's the college wise list of SC category seats in few Government medical colleges through all India qouta:-

• Indira Gandhi institute of medical Sciences, Patna- 2 seats
  
• Nalanda Medical college, Patna- 2 seats
  
• Patna medical college, Patna- 3 seats
  
• Vardhaman institute of medical Sciences, nalanda- 2 seats + 1 SC PH seat
  
• Darbhanga medical college- 2
  
• Jawaharlal Nehru medical college- 3
  
• Government medical college, bettiah- 2
  

For more information refer to the link below:-
http://www.medicine.careers360.com/articles/bihar-mbbs-admission
I hope this helps.
All the best for the future!!