Sentence:  “...What′s your problem, you little shit? Proud of yourself, for ruining <WSD>Mummy</WSD>′s life?” I was careful to use the insipid falsetto the experts commend. “You′ve got Daddy snowed, but <WSD>Mummy</WSD>′s got your number. You're a little shit, aren′t you?″ 
Meaning of the word marked with <WSD> tags:  mother.