How can I ground this charger
This charger came with my MacBbook Pro which I bought from India.
The other end is connected to the magsafe adapter's ground pin. What do I need to insert here?
Solution 1:
You need an international travel adaptor, from the European plug type, specifically plug types E & F, to an Indian plug, type D.
See WorldStandards - Plug & socket types for further information.
If you are a competent electrician, you could snip off the existing 'foreign' plug & change it for a domestic… I would weigh that against not recognising the plug type & solution & say "Don't do that yourself!"
You can get travel adaptors in any airport & usually at stores that cater to travellers, e.g. luggage stores, or generally in tourist areas.
Note: Apple power supplies are multi-voltage, so you don't need to make any allowances for a potential supply difference between the two. [India & the EU are both 240v anyway, but just for sake of completeness.]