Several Sydney Carter songs come to mind - especially "When I needed a neighbour", which seems especially right for this, and is very simple to sing and improvise extra verses for - you'd find it in lots of collections for schools and churches:

When I needed a neighbour were you there, were you there
When I needed a neighbour were you there?
(Chorus)And the creed and the colour and the name won't matter, were you there

I was hungry and thirsty, were you there...

I was cold, I was naked...

When I needed a shelter...

When I needed a healer...

Wherever you travel, I'll be there......

(Tell us how it goes, Knicke, whatever you choose to sing.)