Only that it's a bit early to sound the alarm from a real estate investing standpoint.

@Jason J.Tell her that you have to do a smoke alarm test every 6 months, as well as, a water check.

This time I offered him to leave the house and he says he wants to stay so I hired ADT and the alarm system is installed that same day.

If not, I'd simply explain that you prefer to inspect on your own, but they should give notice to tenant and plan on getting you a copy of current keys and alarm codes, if any.  

First line of defense is an alarm.

Not sure if it was disabled because the battery needed to be replaced or if it was disabled at a time of a false alarm. 

Will they go the entire 10 years without problems.In YOUR experience, what are the most worry free smoke alarms?

If you want to go this route I would recommend getting her out for damaging the property and violating the lease agreement (smoke alarms).The lease I use, and all those in our area, reimburse no a prorated daily basis. 

@Shai Peer I find your post somewhat alarming.

@Rebecca SabotBefore you sound the alarm bells, the "rent stabilization" study isn't a draconian proposal like capping the amount of rent or making it so increases can't be put through.