A.T. Robertson Commentary Colossians 4:15

"Salute the brethren that are in Laodicea, and Nymphas, and the church that is in their house." — Colossians 4:15 (ASV)

Nymphas (Νυμφαν). That is masculine, if αυτου (his) is genuine (D E K L) after κατ' οικον, but Νυμφα (feminine) if αυτης (her) is read (B 67). Aleph A C P read αυτων (their), perhaps including αδελφους (brethren) and so locating this church (εκκλησια) in Laodicea. It was not till the third century that separate buildings were used for church worship. See Ro 16:5 for Prisca and Aquila. It is not possible to tell whether it is "her" or "his" house here.