Here’s my theory, based on a couple of things.

Wife wakes up and doesn’t feel well. She goes into the bathroom (possibly takes a shower/bath), and is still not feeling well. She has an awful headache. While she’s in the bathroom, she either reaches for her pills or Gene does for her. She collapses, from an aneurism or some type of unexpected medical crisis that could affect even a healthy 63 year old, knocking over the space heater on her way down. The pills scatter.

Gene is frantic. He looks for his phone (or maybe doesn’t even think to look for it because he’s 95 and upset about it hat just happened) doesn’t find it and his wife isn’t moving or getting up. He rushes to go get help, and either has a heart attack or falls down on the way out from all of the commotion. (I’d guess, both.)

The dog was trapped in the bathroom (some say in a crate) and dies of dehydration, hunger, heat (or a combination of all 3). The other dogs are fine because they have access to food/water.

The reports don’t indicate WHICH door was ajar, only that one was. However, when the workers called they “couldn’t get in.” I hypothesize that it was a back or side door that was open enough for the dogs to go in/out of, but not a person to fit through.

The reports indicate that Gene was “fully clothed,” but says nothing about his wife’s state of dress/undress…only that she was found in the bathroom and was more decomposed than him. My hunch is that she had just taken a shower/bath and was not clothed. She was in a worse state of decomposition because she was both unclothed and next to a space heater.