Froze when a colleague asked me about my iman

Last week, on a 12 hour night shift in a small Dhaka ward, a worried mother gripped my hand and asked, very quietly, "If I keep dua and he still dies, does that mean Allah didn't answer?" I felt my answers fall away. I stumbled through clinical talk, then left the room with that weight in my chest. I teach myself dua notes between lectures, but I could not explain what to say to her, or how to hold both hope and heartbreak. Now I keep thinking about that question and I want to learn, properly. Has this ever happened to you, and where did you start learning to answer like that?