Using the search function available on A***try for the 1911 census, these are the options for a Mary Martin born around 1904 with a father named William:
Monkstown Farm, Kingstown #3, Dublin -- Catholic
Windsor Avenue, Templecorran, Co. Antrim (noted as Mary Ritchie Josephine)
Ballintemple, Blackrock, Co. Cork -- Catholic
Woodvale Road, Shankill, Belfast (noted as Mary Kathleen) -- Presbyterian
Cableroad Street, Templecorran, Co. Antrim (noted as Maria Dennison Martin).