I was asked recently by one of my brides if she should bring her own emergency kit in case I didn't have the right items. I told her that by all means if there were specific items she needed to go ahead and bring them, but if they were basic items that all wedding coordinators carry, then I should have what she needs.  Here is what I have at every wedding. By the way, after every wedding I usually find one more thing to add.  I can barely lift my case into my vehicle.              

Extra brush or combs                                   
Cell phone, but be sure to turn it off