Green’s Dictionary of Slang

(US) a madam, a proprietress of a brothel.

1853		Life in Boston & N.Y. (Boston, MA) 8 Oct. n.p.: So much for the landlady — now for the boarders.
1879		Nat. Police Gaz. (NY) 27 Dec. 7/4: [Her] energy had secured for her the position of ‘landlady,’ with all the degredation and financial prosperity which that name implies to those who know only its coarsest use.
1935		A.J. Pollock Und. Speaks.
1972		(ref. to late 1950s) B. Rodgers Queens’ Vernacular 112: During the late ’50s [...] Those who managed hustlers [i.e. male homosexual prostitutes] were referred to as landladies and sweet ladies if female while male counterparts were pushers or steerers.
1988		R.R. Moore ‘Hurricane Annie’ 🎵 He told the land lady, ‘I wanna fuck every whore you got. / Don’t worry about the money or what it cost.’.