Mr. White gets the monkeys paw from Morris and wishes for two hundred pounds. This is important because it shows what Mr.White's first wish on the monkey's paw is.
A man arrives to inform Mr.White and Mrs.White that Herbert dies while at work. Also, they are compensating them for their son's death by giving them 200 pounds. This is important because it shows the bad outcome of the first wish, and how Mr.White's impulsiveness is a bad thing.
Mr.White wishes his son alive again. He realizes that he might come back mutilated, so he frantically wishes for him to go away. This is important because it shows how all of the wishes have a bad consequence and it shows how it is badly affecting the family.