Well, I am surprised that she kept her composure enough to concentrate on the road. If it was in fact a water moccasin they did the right thing to stay in the car.
Years ago my brother had a pet snake that he was taking to school for show and tell. Mother was a teacher at our school so she drove all of us. We were unaware until we arrived at the school that Dan's snake had gotten loose in the car and crawled down the crack behind the back seat. Mom said he would be fine down there until we got home because she didn't have time to get him out before the bell rang. After school she got back in the car and offered to drive us all home. My sister and I walked! I can still hear the language coming from the carport as my dad dismantled the car looking for that lousy snake. He was never seen again. (Don't know if he escaped or Dad found him and lost him somewhere.) Ann in TN