This looks like a couple old enough to be empty nesters so only the two of them in the house.
Besides, they called out to the intruder and yelled that they had a gun. I figure they wouldn't have shot if she had responded to them.
I know if I'm scared, warned the intruder and the only answer I got was the continued approaching footsteps, I'd shoot.
If the intruder had been a 6'3" muscular, male, habitual criminal, we'd be saying how stupid the homeowners were for playing 20 questions before protecting themselves.
You got that right.