Is "moron" one of those nouns that doesn't change really between the singular and plural words?
No, moron is the word for "carrots". "A carrot" is "Moronen".
Now I see :). Diolch yn fawr.
Wyres is the female version of ŵyr ("grandson, grandchild"), which is cognate with Latin puer ("child, boy"), source of English puerile.
It sounded like she's saying ''yn hoffi moron''. I have to listen really closely.