After passing Mechanical Engineering you can apply for any specialization in MBA course . you have to take admission in MBA Specialization according to your own interest and ability .

Here for your reference I am giving you the list of some of the best specializations in MBA:
Manufacturing Systems Engineering
Industrial Engineering.
Mechanical Handling and Automation
Pollution and Noise Control.
Computer Aided Design.
Mechanical Systems Design
Computer Aided Manufacturing.
Combustion and Propulsion
Heat Transfer and Thermal Power
Thermal Energy and Environmental Engineering
I.C. Engines and Gas Turbines
Refrigeration and Air Conditioning
Engine Technology
Automobile Designing
Production Engineering
Combustion Technology
Applied Mechanics
Engineering Analysis and Design
Industrial Automation and Robotics
Manufacturing and Precision Engineering
Mechanical System Design
Refrigeration and Air-Conditioning
Thermal Turbo machines
Turbo Machines
CAD/CAM
Automotive Engineering
Engineering Mechanics
Machine Design
Mechanical System Design and Dynamics
Mechatronics
Thermal Power Engineering
Tool Engineering
Accounting
Consulting
Energy and Natural Resources
Entrepreneurship
Finance
Health Care / Pharmaceuticals / Biotechnology
Industrial Management / Manufacturing
Information Technology (IT)
Luxury Brand Management
Marketing
Operations Management
Public Sector Management / Government
Real Estate
Retail and Consumer Goods
Strategy / Business Development
Supply Chain Management
Sustainability / CSR / Social Entrepreneurship
Tourism / Hospitality / Leisure
Product Management
Retail Management
Sales & Marketing Management
Strategic Management
Telecom Management