As per momentum conservation theory
If net force on a system is zero then initial momentum of the system will be equal to final momentum of that system.
Since initially coconut is at rest so initial momentum is zero
Here it break into three pieces such that two parts of same mass while third part is of double mass
now we can say
here we know that two parts fly off with same speed v0 along south and west directions
now we will have
so here magnitude of the speed of the third part will be
and the direction of the third part will be along North East direction