One of my cousin had to travel to Asia because of some emergency situation. I paid a huge price for the earliest available flight, but the airline (United) dropped him at the destination 12 hours late. When asked, they were compensating him with 200$ of airline credit. As I said it was an emergency and he had a huge bump because of that. Is that all he can get from airlines as compensation?
Technically no compensation is due - there are no US or India regulations that require airlines to provide compensation in cases like this. If the flight passed through Europe then there are some regulations that may have been relevant, but presuming it was United Airlines all the way then it would not have been via Europe.
United Airlines typically does compensate for extended delays, in the form that you've stated - either a credit for future travel, or a number of miles. The exact value will depend on his status with United.