"ਏਕੇ ਕਉ ਸਚੁ ਏਕਾ ਜਾਣੈ ਹਉਮੈ ਦੂਜਾ ਦੂਰਿ ਕੀਆ ॥
He knows the True Lord as the One and only; he sends his egotism and duality far away.
ਸਗਲ ਭਵਣ ਕੀ ਮੂਰਤਿ ਏਕਾ ਮੁਖਿ ਤੇਰੈ ਟਕਸਾਲਾ ॥੧॥
Yours is the one and only form of the entire universe; Your mouth is the mint to fashion all. ||1||
are these feminine or masculine use?"
in second verse, ਏਕਾ is feminine because ਮੂਰਤਿ is feminine and ਏਕਾ is related with it.
in first case, ਏਕਾ is not used as an adjective and not used with any noun. its not an adjective of any noun - masculine or feminine. this verse is not relevant in this debate.