i would tell guest B that guest A meant well to let them in, but your home was left in a vulnerable state, since no one closed the windows before leaving the property. Ask guests B to reread the rules their booking requires them to obey, because you need to know that they understand them and do not want another mishap. You might suggest that they tell a host when they expect to arrive at the property if they want to leave luggage, so the host can arrange to be there. Then follow up with how horrible it would have been for you to be told that their luggage was missing, when you hadn't even known that they had left it, because your check in time is late in the day and you had no warning that they wanted to leave bags ahead of time.
I'd give guests A the review that would have been given had they not left with the windows open, then in the private message explain that you understood they were trying to help, but that your home could have been burglerized, because the windows were never closed and you found them open when you arrived home from work.
It sounds like guests B arrived when your son was already out of the house, so encouraging guests to give you a time of "arrival at the property" would prevent this from happening in the future. The worst thing about the entire scenario is that if something went wrong, you can bet you'd get a less than stellar review.
Your rules are very clear, but I actually had a hard time finding them on the listing, so another preventive fix could be to ask every guest during booking to take another look at the full list of house rules, since their booking requires their adherence to the rules.