Mac Oiste
Mac OISTE—V—M'Coisht, M'Coiste, M'Costy, MacGusty, Hosty, Hasty, &c.; 'son of Hodge' (a 'pet' form of Roger); the name of a Mayo family of Welsh origin, so called from an ancestor named Hodge Merrick, who was killed in 1272; also written Mac Hoiste, which see.
Alphabetical Index to Irish Surnames