Linguists Discover Previously Unidentified Language In Malaysia

They imply it's in the Austoasiatic language subfamily Aslian¹: "Some of these words suggested a link with other Aslian languages [...]".

Austoasiatic² is the family that includes Vietnamese and Khmer, but not Malay.

1: https://en.wikipedia.org/wiki/Aslian_languages

2: AKA Mon-Khmer https://en.wikipedia.org/wiki/Austroasiatic_languages

Regarding the words for mother all around the world, I have little doubt that we all speak the same language, only vastly different varieties. I'm getting into semantics, but in this case, semantics seems on-topic :)

It's evolution. Isolation=diversity.