Considering all the possibilities, a feasible solution is that the wife was about to defrost the dinner but at the same time a few thieves broke in, falling short of ways to save herself she pressed 911 on the microwave timer (this can be safely assumed as it is nowhere mentioned that the food was actually being defrosted, only the microwave was on). She did this on purpose as she knew it was time for her husband to come. Now as the thieves heard the sound of the door opening they dragged her to the bedroom and told her to reply to his husband so that he doesn’t suspect that there’s someone else in their home, but little did they knew that she had already planted her message. Hence the husband called 911.