Elementary my dear Mikey....
Wissous was a small village now swallowed up with the development of Paris-Orly airport Antony/Rungis etc.
There was a standard gauge tramway called the Chemin de fer Paris-Arpajon. This was all closed down by 1937 so the woman was very immodestly dressed for the period.
Notice it says 'Wissous S et O.' This is the old departement Seine et Oise. Which covered all of Paris from below the river Seine in the South to above the river Oise in the North.
The area of Wissous is now in the departement Essonne (91).
The funny looking coach is a double deck coach with an open top deck.