A noun for “mother” in The Etymologies of the 1930s derived from the (Noldorin-only?) root ᴹ√NAN (Ety/NAN). It apparently replaced archaic/poetic N. †emil (Ety/AM¹; EtyAC/AM¹).
Conceptual Development: The Gnomish Lexicon had a similar set of words for “mother”: G. maba, mabir, baba, and mavwin from the early root ᴱ√maƀ “something nice” (GL/57). The last of these appeared as G. mavwen “ancestress” in the Gnomish Lexicon Slips modifying that document, with an archaic meaning of “mother” and variant forms mafwyn and mavuin (PE13/115). In these slips, it seems the normal “mother” word was G. nân (originally glossed “father”) with variant nanwin (PE13/115). This last word is likely the direct precursor of N. naneth.
Neo-Sindarin: I would use S. emel from the late 1960s as the normal word for “mother” in Neo-Sindarin, but would retain N. naneth as a dialectical or more formal variant.
A prefix for “snake” in The Etymologies of the 1930s derived from the root ᴹ√ANGWA of the same meaning, most notably an element in N. amlug “dragon” (Ety/ANGWA).