Pwllheli Royal Mail Delivery Office | Collection Office | Post Office Parcels - United Kingdom

My mother (88) recently passed away in birmingham and she was born in pwllheli. Im trying to find the location of the address on her birth certificate in 1926. Her name was megan griffith and the address written is TY CAPEL, RHOSFAWR, ABERERCH. Any help you can give is most appreciated? Malcolm Diamond