In details, explain Malcolm and Donblain’s re action to the ordeal?

Are you referring to their father's murder? They both feel unsafe. They think that they will be the logical targets of guilt over their father king's murder, 'the near in blood, the nearer bloody. ' People will think they killed King Duncan to further their succession to the throne. Donalbain flees to Ireland and Malcolm flees to England. This temporarily works in Macbeth's favour.