The correct option is "some". The word "some" is used when referring to an unspecified quantity of countable or uncountable nouns like "coffee".
The sentence becomes:
I’ll get you some coffee.
The correct option is "some".
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?