Because I was nice to you, you owe me, due and payable on demand.

So I went over the managers head and asked to see where in my job description it says I have to give an employee a ride home.  He said it doesn't.  I said you need to tell your manager to stop telling me I have to, and have her stop asking other employees to give her a ride home too.  It just comes down to them being bullies.  They are part of a cliche and each benefits from the others shadow side.  It is tough to navigate this type of interpersonal relating.  But it is what I always encounter in groups of people.  There is no getting around it.