before everyone were trying to prevent MIB from leaving the Island, cause if he left, then everything exist will be no longer exists.
Mother said inside each man there a little bit from that light, also she said people will try to take it, and she said: "And if the light goes out here... it goes out everywhere. And so I've protected this place. But I can't protect it forever. "
my thought now is, is it possible the light now is inside the MIB, and this is the real reason they need to stop MIB from leaving?