Mummy vs old lady

Mummy

name

  • One's mother. 

old lady

noun

  • The Bank of England, sometimes referred to as the “Old Lady of Threadneedle Street” or simply “The Old Lady”. 

  • A queen. 

  • One's mother. 

  • An elderly woman. 

  • One's girlfriend, wife or significant other. 

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