Answer: Post-traumatic stress disorder
Step-by-step explanation:
Post-traumatic stress disorder (PTSD) is a mental disorder which occurs due to an individual witnessing or being exposed to a fearful or dangerous events or traumas which with time causes such individual to develop symptoms of post-traumatic stress disorder such as difficulty in sleeping due to nightmares,lack of concentration, occasionally on guard, irritations etc.
Here, Pukari suffers Post-traumatic stress disorder as a result of the fearful experience he witnessed in the killing of his wife and children and so has developed symptoms of the disorder such as lack of concentration due to recurring flashbacks causing him have difficulties at work.