Look, if you're the President, and there's this high-profile mother-of-a-dead-soldier who wants to meet with you, you should just do it. As painful as it might be to hear this woman rail against you, saying things like "Why did you kill my son? What did my son die for?", you go ahead and give her a few minutes. Yes, yes, I know, she already talked to you, but she wants to talk to you again.
If you believe that your war is right, and that the kind of patriotism that takes a life is tragic but necessary, you tell her those things. You're Commander in Chief, and she's a grieving citizen of the country you lead. Talk to her.
If you ignore her, or fob her off, or have security threaten to have her arrested, you look like you don't believe in your own cause. You look like a chicken-hearted coward afraid of facing someone who is in pain as a result of an action that you are ultimately responsible for. It's not a good impression to make.