On page 39, why are the girls hung in Auschwitz shown on the road on which Vladek, Art, and Françoise are driving?

I believe the panel you are referring to is from page 79 of Art Spiegelman’s Maus II: A Survivor's Tale: And Here My Troubles Began. Here Spiegelman illustrates girls’ feet and legs hanging down from the top of the panel as Vladek, Art, and Françoise are driving away. Spiegelman includes this image to show that the horrors of what Vladek experienced during the Holocaust are always with him. In the comic, Spiegelman brings up the story of prisoners that blew up a crematorium and killed three S.S men. Vladek replies, “Yah. For this they all got killed.” To Spiegelman it is a story, but to Vladek it is his past.

And the four young girls what sneaked over the ammunitions for this, they hanged them near to my workshop. They were good friends of Anja, from Sosnowiec. They hanged a long, long time..sigh.

For Vladek a simple inquiry from his son brings back the horrible image of the young girls hanging. Spiegelman, the author and artist, represents the ever-present nature of Vladek’s nightmarish past by having a past event visually mixed with a present moment.