I'm receiving C-Band signals on my 100cm (~3.3") dish. So you should be able to get C-Band signals on your 4" dish.
C-Band signal which can be easily caught in India with smaller dish are .....
1. Asiasat 5/7
2. Insat 4A
3. Measat 3
4. Thaicom 5/6
5. Intelsat 20/17 etc .....
Here is my thread on same
Caught IS20@68E C-Band with 100cm offset dish