The Question and Answer section for A Raisin in the Sun is a great resource to ask questions, find answers, and discuss the novel.
I'm not sure what part of the play you are referring to. I recall he wants to give his son money. He gives him a dollar at one point.
Mama tells Beneatha to watch the way she is spreading the roach poison, inferring she might get some of it on Travis. Beneatha answers that she doesn't believe it would hurt her nephew because it doesn't seem to hurt the roaches..... they can...
The are a variety of different arguments in A Raisin in the Sun. Which specific argument does your question pertain to?