TOEFL

6 Tips for Getting into an MD/MPH Program
Understand how public health and medicine are interrelated.
Take relevant courses that complement public health.Apply your learning and get field experience in public health.
Make a list of MD/MPH programs to apply to. .
Communicate your genuine interest in public health in your medical school essays and interviews.

I have heard of the universities like MIT, Berkeley and Princeton.

IELTS or TOEFL either works. GRE will depend on the university under consideration.

A GRE score above 315 should be targeted and a TOEFL of 90 to 100. It is better you check some university websites for the admission requirements, you will be able to prepare in a better way if you have a target and goal in mind. Different universities have different criteria.

Scholarships are based on merit, they are given by the universities (you are applying to) to deserving students. Generally applicants are considered by default and the most meritorious ones are considered. Very good academic grades, a good GRE score, above 310, TOEFL score above 100, extracurricular activities, SOP, recommendation letters etc. Are evaluated.