re Manx genealogy in general try
assuming it is McGain (you must admit that your request was not exactly helpful to any that could help!)
the name is not Manx - two occurances in victorian directories
1881 McGain, Mrs. Isabella, Ballasalla
1894 McGain, Thomas, Glen View Port Erin
in 1881 census
Malew Farm House 2 Ballthane Ballasalla MC GAINE Henry Servt - M 14 Farm Servant (Indoor) Castletown IoM
Malew Ballasalla MC GAIN Isabella Head M F 51 --- born Down County Ireland
Malew Ballasalla MC GAIN Elloner Daur U F 25 General Servant Malew IoM
Malew Ballasalla MC GAIN William Son U M 20 Laborer Malew IoM
Malew Ballasalla MC GAIN Robert Son U M 11 Scholar Malew IoM
Malew Ballasalla MC GAIN Isabella Daur U F 7 Scholar Malew IoM