Hi,
There's a Cae'r Ferch, Cae'r Ferch Isaf, Cae'r Ferch Uchaf and Cefn Cae'r Ferch, with variations to these spellings; sometimes the (') is left out. I've also seen 'Erch' rather than 'Ferch'; the river Erch passes very close to these farms and flows into the sea at Pwllheli.
The family I have connections with lived at Cae'r Ferch and Cae'r Ferch Uchaf. The family you refer to, lived in one of the other two.
Richard Lewis b. c.1870, married Sarah Davies of Trefor (Trevor), a sister of my maternal grandmother, in Conwy Reg. District, in 1898. At one time they kept a small hotel/guest house at Craigydon, Llandudno.
Emyr