If Barb finds him dead, well there will be an obit and I'm sure Anna will be told somehow and then we'll find out
If Barb's dead and there's no one to find him... well then it'll be a few weeks while he sits there and rots and then someone will finally make a wellness call (like Anna) and the cops will come and they'll break down the door and they'll eventually find him in that mess... hopefully. That's how the old man down the street from me was found. It was summer, his yard hadn't been mowed in months, the mail was piling up, and his car was still in the drive way. I'm told he was found in the bathtub and according to my folks, he had been taking a bath when he had a heart-attack and because of all that stuff that happens when you die in water the cops came out of there and one of them puked. Must have been bad. That'll probably happen when Chris dies alone.
BUT on the bright side. When Barb dies, Chris won't be able to afford the house anymore, or keep it clean, and he'll probably be sent to a "home" and they'll be the ones to find him.