There are two truths in this passage, and, unfortunately, they do not coincide.There is the author's truth and there is a mother's truth.
No mother in her right mind would say that her son was lucky because he did not have to kill a conscript, but the author feels that way. War is a terrible thing. It is premised on on the notion that the "team" that can inflict the most damage or kill the most number of the enemy is the winner. The rules are, there are no rules. Anything goes.
So the first sentence I would pick would be the one beginning. "I thank my God he did not have to do it..." That is the author's point of view.
The second sentence I would choose is "What you got black on for ...? " This may not be what your marker is looking for, but on principle I would pick it. She is saying "We should not mourn his death. We shouldn't celebrate it either. The only good thing is that his death meant that someone else didn't die."
This last sentence is the hardest to justify. Most women I know couldn't live with the unnecessary death of a child. But the author could. He could say that such a death was needless and pointless, and should not be mourned.