Hi Siji, you are correct both the answers are correct. In fact
All the answers are gramatically correct!
We feel that it was unnecessary for them to react so violently.
You are feeling that it was unnecessary.
We felt that it was unnecessary for them to react so violently.
Same as above only in past tense. also means you are still feeling the same way.
We have felt that it was unnecessary for them to react so violently
You were feeling it was unnecessary but now feel otherwise
We had felt that it was unnecessary for them to react so violently.
Same as above but in past tense
On the whole the question itself needs some tweaking.
Cheers
kumar