My thought is that if/when she asks for a ride, then YOU decide if it works for you to drive 3 hours to bring them back. I get your missing your children, but it seems to me that you are trying to impress her with your generosity. It also sets up the "why would you offer now when you didn't before?" Be consistent in your detachment. A marathon, not a sprint. Good luck.
The only easy day was yesterday
Friends - 35 years Together -32 years Married - 29 years S - 26 BD - 11/11 S 7/12 Last visual contact 2/13 Last verbal contact 4/13