mammy vs mither

mammy

noun
  • mamma; mother 

  • In the southern United States, a black nanny employed to look after white children; or in the antebellum South, a female slave who was close to the household and looked after the children. 

mither

noun
  • mother 

verb
  • To pester or irritate someone. 

  • To make an unnecessary fuss, moan, bother. 

How often have the words mammy and mither occurred in a corpus of books? (source: Google Ngram Viewer )