Never leave people to their own devices! She should have been chaperoned at all times. And even if she wasn't being chaperoned at all times, she's 18 years old, she knows better than to wonder off without telling someone, especially in a foreign land. I pray for her safe return.
Yes provided she was sober. A tv show recorded drunken girls being led by men at 2 in the morning. If the cameraman didn't go over and tell the guy to beat it, who knows what would have happened?