Well thanks to all for your suggestions ... in the end my daughter described the song, rather than actually quoting lyrics. But it was fun looking through the songs suggested, & I learned quite a few new ones I might otherwise never have discovered!
I will take the liberty of quoting from my daughter's story ...
"Joan trudged after Mary, drying her eyes on her apron. In the sudden tranquillity, Joan realized that someone was singing a song that was vaguely familiar. A sad song, hauntingly beautiful. She glanced up, and saw an old, limping man, with a long white beard, carrying only a cane and a small cloth bag, wearing threadbare clothes. Why was anybody on this little back road at all? It only went from the farm to the house. The man must have come out of the woods. But the song! It was about returning home after many years away. That's where she had heard it before! When she was very small, Father used to sing it while Uncle David played the fiddle, before they both left to fight for the King against the revolutionaries. The song brought back so many memories, it almost felt as though the war had never happened."
The old man turns out to be Joan's father, returning home in disguise, and the rest of the story chronicles the family's flight from the United States, to settle as Loyalists in Upper Canada.
Happy New Year to you all!