mammy vs mauma

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. 

mauma

noun
  • mother 

  • A title of respect for an elderly woman 

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