(For my cat,) This would always works to make her get her fuzzy ass back home. (Indoor 85% but we let her out once in a while, especially in summer.)Her food dishes are like aluminum or something close. When she was little (she's 5 now) whenever we'd feed her, and she wasn't in the immediate vicinity...We would bang on the dish with silverware. Like magic, She'd come out of her nice cozy spot up-stairs, and we'd here the quick thump-thump-thump of her jumping partially down the stairs and running to where she's fed.
When she's been out side for hours, we circle the neighborhood just idling down the two streets parallel to ours, banging away on a food dish.
If we didn't find her waiting for the door to open so we could let her inside, we'd go out on another dish-banging trip approx 30 min later. After only a max of two trips, she finds her way home.
Now I'm not sure what the cat's feeding routine is, find out from the humane society. Ask them to go through the steps with you, that they'd take to feed the cats. Maybe there's some noise that'll attract it. All else fails take a stroll through the neighborhood with a paper lunch sack with some cat food in it, It'll sound close enough to a real food back, yet not be so heavy.
Best of luck and so very sorry for your loss. As other's have stated, he died peacefully and comfortably in his home.
