Currently, my YOE is around 3 as System Eng, and Grade is C1. When will I reach C2, and what will be the package if my current CTC is 9 LPA?

You will not be promoted for a couple of years atleast.

(Your team will already have C2s who get lesser pay than you with more YOE)

In next decade with 5.1 LPA they will surely promote you