#1 Why did Raghu kill Koko?
Because she was gutless and didn’t turn in her husband even after knowing of his crime. Not reporting a crime is as much a crime.
#2 Why did Raghu use the NGO worker as a pawn?
Because she came all gungho to save the criminal, but never showed any empathy or sympathy to the people who suffered because of his crimes. Basically, the same thing realtime NGOs face in India.
#3 Why did Raghu not give the money to the police inspector?
Because according to him, he was incompetent in finding the real culprit and closing the case. Incompetency is something that one cannot digest right after personal loss.
#4 Why did Laik give himself up and confess?
Because, even after all his failings, he loved the two women in his life, and felt a pang of defeat when his mother had nothing to tell good about him. He decided that he would not go unsung into the night. Basically, legacy bhai.