John Williamson from Australia has a great song about his Grandfather called "Old Lou".
"Grandfather's Clock" has the element of growing old in it. Eric Bogle has a number of songs about old people. He has a song about an old farmer (The Cockie?); a song about an old lady who dies alone in her appartment (can't recall the title); a song about an old soldier visiting the grave of a fallen comrad and thanking him (A Gift of Years? There are a bunch more out there.