How many persons are standing exactly between I and O?

M is standing third to the right to H and M is standing at one of the extreme ends, => let M is standing at right end, thus H is facing north direction. 

L is standing third to the left of H, => L is standing 2nd from left end. 

I is standing between J and M, => J is standing to the immediate right of H and I between J and M.

N is not an immediate neighbour of H and one of the immediate neighbours of L is K who is facing north, => O is standing to the immediate left of H.

The immediate neighbours of O face opposite directions with respect to each other, => since H faces north, the other neighbour has to face south (which can't be K), thus N faces south direction and stands between L and O. Thus, K stands at extreme left end facing north.

The persons standing at the extreme ends face the same direction, => M faces north

The immediate neighbours of J face north, => I also face north.  

Not more than four persons are facing north, => L, O and J face south direction.

2 persons (H,J) are standing exactly between I and O.

=> Ans - (D)