What instructions does Monsieur Gavard give La Sarriette as he is being escorted to jail?

In a surprising turn of events, old Monsieur Gavard is arrested after the police find "Ambrose," the revolver. As he is escorted to jail, Monsieur Gavard manages to slip a house key into La Sarriette's hand, instructing her to clear out his rooms and burn his personal papers. Although Madame Léonce is at first reluctant to allow the three harridans into Monsieur Gavard's rooms in the Rue de la Cossonnerie, she finally relents.