Step 1: Understand “Even if” structure.
The phrase “Even if” means the action will happen regardless of the condition mentioned.
Step 2: Interpret the meaning.
“Even if it rains I shall come” means rain will not stop the speaker from coming.
Step 3: Match the correct equivalent.
Option (c) directly expresses certainty of coming under both conditions—rain or no rain. Other options contradict or distort the meaning.
\[
\boxed{\text{(c) I will certainly come whether it rains or not}}
\]