As per me MBA is PG course and after it you should go for phd in management not for any diploma program , here I am telling name of some of the good colleges/universities which offered phd in management

Amrita School of Business, Coimbatore - Ph.D in Management
Apeejay Institute of Management Technical Campus - Doctor of Philosophy in Management
Baddi University of Emerging Science & Technology - Doctorate of Philosophy in Management
Birla Institute of Technology Extension Centre, Patna - Doctor of philosophy in Management
Centre for Distance Education, Shivaji University - Doctor of Philosophy in Business Administration
Centre for Distance Education, Shivaji University - Doctor of Philosophy in Business Management
Centre for Management Studies, Dibrugarh - Doctorate of Philosophy
Chaudhary Devi Lal University - Doctor of Philosophy in Business Administration
CMR Institute of Technology - Doctor of Philosophy in Business Administration
CMR Institute of Technology - Doctor of Philosophy in Business Administration
Department of Pharmaceutical Education and Research - Doctor of Philosophy in Management
Dibrugarh University, Dibrugarh - Doctor Of Philosophy in Business Administration
Dr.G.R.Damodaran College of Science - Doctorate of Philosophy in Management
Faculty of Management Studies, Banaras Hindu University - Doctoral Program in Management Studies
G.L.A. Institute of Business Management, Mathura - Doctorate Of Philosophy in Management
G.L.A. Institute of Business Management, Mathura - Doctorate Of Philosophy in Management
Gauhati University - Doctor of Philosophy in Business Administration
Goa University - Doctor of Philosophy in Business Adminstration
Guru Ghasidas Vishwavidyalaya - Post Doctorial In Business Administration
Himachal Pradesh University - Doctor of Philosophy in Business Administration
IBS Business School, Jaipur - Doctor of Philosophy in Management
Indian Institute of Business Management & Studies - Professional Laureate in Management ( PLM)
Indian Institute of Business Management & Studies - Professional Doctorate in Management (PDM)
Jain University - Doctor of Philosophy in Management
Jaipur National University - Doctor of Philosophy in Management
Jamia Hamdard University - Doctor of Philosophy in Management
Jamia Hamdard University - Doctor of Philosophy in Health Management
Jawaharlal Nehru Technological University School of management Studies, Hyderabad - Doctor of Philosophy in Management
Jayoti Vidyapeeth Womens University - Doctor of Philosophy in Management
Kalpataru Institute of Technology - Doctor of Philosophy in Business Administration
Loyola Institute of Business Administration - Ph.D. Degree in Business Administration
Madurai Kamaraj University, Madurai - Doctor of Philosophy in Business Administration
Maharaja Krishnakumarsinhji Bhavnagar University - Doctor of Philosophy in Business Adminintration
Mahatma Gandhi University, Kottayam - Doctor of Philosophy in Management and Business Studies
Mahatma Jyoti Rao Phoole University, Jaipur - Doctor of Philosophy in Management
Mangalore University - Doctor of Philosophy in Management
Mohanlal Sukhadia University - Doctor Of Philosophy In Business Administration
National Institute of Management - Professional Doctorate in Management Studies
Nirma University - Doctor of Philosophy in Management
PES University, Bangalore - Doctor of Philosophy in Management
Pondicherry University - Doctor of Philosophy in Management
Rizvi Institute of Management Studies & Research - Doctorate of Philosophy in Management Studies
S.N.S College of Technology - Doctor of Philosophy in Business Administration
Sant Gadge Baba Amravati University - Doctor of Philosophy In Business Admimistration
Saurashtra University - Doctor of Philosophy in Business Management
Savitribai Phule Pune University - Doctor of Philosophy In Management
School of Management Studies, Pondichery University - Doctorate of Philosophy in Management
School of Management, KIIT University, Bhubaneswar - Doctor Of Philosophy
Shivaji University - Doctor of Philosophy in Business Administration
Shivaji University - Doctor of Philosophy in Business Management
SoftBrain Informatic Technology Pvt. Ltd - Doctor of Philosophy in Management
Srinivas Institute of Technology - Doctor of Philosophy in Business Administration
St. Joseph Engineering College - Doctor of Philosophy in Business Administration
T John College (TJC), Bangalore - Doctor of Philosophy in Business Administartion
T. John Institute of Technology - Doctor of Philosophy in Business Administration
Teerthanker Mahaveer University - Doctor of Philosophy in Management
University of Allahabad - Doctorate Of Philosophy In Business Administration
University of Calcutta, Kolkata - Doctor of Philosophy in Business Management
University of Hyderabad - Doctor of Philosophy Programme in Management Studies
University of Hyderabad - Doctor of Philosophy Programme in Management Studies
Utkal University, Bhubaneswar - Doctor Of Philosophy in Business Administration
Vel Tech Dr.RR & Dr.SR Technical University, Chennai - Doctor of Philosophy in Business Administration
Visvesvaraya Technological University - Doctor of Philosophy in Business Administration