"Fama wajadna fiha ghayra baytin min al-muslimin" (And We found not within it other than a household of Muslims) means: the household of Lot in terms of kinship, and those who were with him from among the believers.
﴿فَمَا وَجَدْنَا فِيهَا غَيْرَ بَيْتٍ من الْمُسلمين﴾ يَعْنِي: أهل بَيت لوط فِي الْقَرَابَة، وَمن كَانَ مَعَه من الْمُؤمنِينَ.