The runaway maid

I just got to know my friend's maid ran away from home last midnight. She even left the door unlocked! How irresponsible of her to do so. Luckily, my friend's husband woke up in the middle of the night to get a class of water from the kitchen. I just can't imagine what could've happened if the door kept opened until the next morning and there's plasma TV and expensive sound system sitting in the living room.I suggest my friend to install alarm system monitoring before she employ her next maid. At least they can activate the alarm before going to bed. Any movement at any contact point around the house will surely trigger the alarm.