First of I want to offer my condolences to you and to the family.
As far as a song choice -- I still have to side with "You'll Never Walk Alone" as being the best one. I have heard it done numerous times at funerals and for other religious services and it has always come across well.
Another song to think about that you would probably never consider is "You Walk With Me" from
The Full Monty. Out of the context of the show the lyrics work very nicely for a service such as this one. Obviously it was meant to be a duet, but could be done as a solo since there is always a defined melody line and no polyphony. Here are the lyrics in case you aren't familiar with them:
Is is the wind
Over my shoulder?
Is it the wind that I hear gently whispering
Are you alone there in the valley?
No, not alone for you walk, you walk with me
Is it the wind there over my shoulder?
Is it your voice calling quietly?
Over the hilltop, down in the valley
Never alone for you walk with me
When evening falls
And the air gets colder
When shadows cover the road I am following
Will I be alone there in the darkness?
No, not alone, not alone
And I'll never be...
Never alone, you are walking
You're walking with me
Is it the wind there, over my shoulder?
Is it your voice calling quietly?
Over the hilltop, down in the valley
Never alone for you walk with me
Over the hilltop, down in the valley
Never alone for you walk with me
"You pile up enough tomorrows, and you'll find you are left with nothing but a lot of empty yesterdays. I don't know about you, but I'd like to make today worth remembering." --Harold Hill from The Music Man