I assume the dog died from thirst / dehydration. It was found in a crate / kennel or in a closet.
So the wife died first, the dog maybe 3-4 days later. And then Gene died from a heart attack. He had advanced Alzheimer’s, so he wasn’t able to take care of himself or call for help.
ah yup- could be- supposedly a person can only live 3 days or so without water-
same for ther dog too- probably died of thirst- uggh-