After 10th

Hello Srinivas, it's very nice to SEE the enthusiasm of a parent for welfare of child. I feel that you can take admission in any college in your city but encourage child to understand the subjects well since this will enable him to pass NEET with flying colours. It's actually the ranking in NEET that will decide his fate. Best wishes to you and your son.

The eligibility criteria of Graduate Marine Engineering (GME) is given below.
Eligibility : BE or B.Tech (Mechanical or Naval Arch) from AICTE approved college/university with minimum 50% marks and at least 60% in English in either 10th or 10+2. Fluency in written and spoken English is expected.
So from above Diploma Mechanical engineering students are not eligible for this course.