"Lullabye" by Billy Joel- I was in college (1994) and made it back home in just enough time to say goodbye to my grandmother, who was dying of cancer. When I walked into her hospital room, she grabbed my hand and said, "You came!" She died within 2 hours after I arrived.
When my mom, aunt, and I got into the car after leaving the hospital, we heard the opening to "Lullabye". I had never heard the song, but the opening lines made my mom, aunt and I look at each other in amazement- "Good night my angel, time to close your eyes"
I never heard the song's title, so I didn't know it was Billy Joel. My mom heard the song again when her and my aunt were packing up my grandmother's house.
A few years later, at my school's book fair, I see a beautiful hardcover book with a CD included of that very song! I bought it and let my DH listen to it. He plays piano by ear and was able to play the song (and still does).
The weird thing is, my DD Lindsay was 4 at that time. I told her I wanted her to listen to a very beautiful song. When I played it for her, she burst into tears

It was such an unexpected reaction, and when I asked her why she said the song just made her feel sad.