I am curious where the dog was found in the house and what its demeanor was. Does it maybe sleep with the kids? Or perhaps the intruder shut it up in a room?
Also curious about possible service people they've had in their house recently. Could be they had people working in the home and for ease of coming/going, gave out their door code and someone came back? Either for robbery or maybe some type of grievance if there had been displeasure with the service.
While I am typically in agreement that if we are looking at midnight to about 8 AM, they likely wouldn't have let someone in voluntarily during those hours of the night, if the person was a close friend or acquaintance and showed up in distress, I could definitely see opening the door to them. I am thinking of my best friend pounding on my door at 1 AM, crying, upset, and I would not stand there and refuse to let them in because the hour is late. My first reaction would be, I know them, we're close, they need help, and I open my door to them. Not suggesting this was their best friend - just using that relationship as an example. Another thought: if they were very trusting and generous people, would they be inclined to open their door even for a stranger who was in distress?