As far as picking Medical Science as optional subject is concerned, you can; if you are consider you will be able to do justice with it.
In recent years, Medical Science is among the best performing optional subject and many of top rankers like Artika Shukla (AIR 4; CSE 2015) Indu (AIR 30; CSE 2015) and Ravi Mittal (AIR 61; CSE 2015) have achieved brilliant success with Medical Science as optional subject.
You have to decide the language you wish to opt for writing examination. in case you are considering Medical Science as optional subject; English medium should be preferable as you have limited resource available in Hindi.
Have a look at the syllabus and previous years' question papers to know the level and current trends. After considering all aspect, take a rational decision.