Find the missing character?

Answer: Option C

Logic (Row-wise):
Left Hand Letter + Right Hand Letter = Central Letter.
Coding, A = 1, B = 2, C = 3, D = 4, E = 5...I = 9 .... M = 13,..... Y = 25, Z = 26.

E + H = 5 + 8 = 13 = M
N + A = 14 + 1 = 15 = O
So,

I + D = 9 + 4 = 13 = M.