In this scene from "A Raisin in the Sun," Mama (Lena Younger) has just told Walter that she will not allow him to invest the family's insurance money in a risky business venture. She tells him that she would rather see the money go to waste than to see it destroy her son, and she tells him that he must take responsibility for his actions and be the head of the family, as he is supposed to be.
After saying this, Mama takes the insurance money from Walter and gives it to Beneatha, her daughter. This act of defiance and strength changes Walter's mood, and he is suddenly filled with a sense of determination and purpose. He realizes that he has been acting recklessly and selfishly, and that he must take responsibility for his actions and be a better husband and father.