I’d go with murder, not premeditated. He didn’t go hide in their house.
Sorry, but when you set up a mantrap that defacto shows premeditation. If I have my car stolen multiple times, then I decide to put in a device that would electrocute anyone who broke into my car, and someone breaks in to my car and is electrocuted to death, I’ve just committed premeditated murder... I created a man trap with the intent full well to kill someone, whether or not I knew at the time of that decision who that person would be.
This guy planned to kill, there is no doubt about premeditation, he may not have known who his victims exactly would be, but he planned to kill. That’s premeditation.