Everyone knows that you shouldn’t be late for a job interview, so consequently, few, if any, are, regardless of their actual performance. Even the laziest, tardiest, most no-call/no-show sleep-till-noon-oh-sorry-I-was-sick person is going to make it to the interview on time. Using the fact that she was late to assume this means she is going to be tardy all the time is just plain silly. She probably really did get lost, because being late to a job interview is pretty much unthinkably stupid if you have any hopes for the job.
So I wouldn’t hold it against her for being late. It can happen to the best of us. Well, maybe a little bit.
There’s always a silver lining though… Think of it this way. She was lost and late to her interview. In her position, I would have probably written it off as a lost cause and went home. She admitted her mistake, called you up, and asked for help, and went ahead with the interview even though she knew it probably killed her chances. Could that not be interpreted as a willingness to get help to fix a problem she cause, even if the situation is embarrassing and could hurt her career chances?