In terms of proper English it would be the mother because she is the subject of the sentence whereas the daughter is the object. The subject is the one performing the verb and the prepositional phrase applies to the verb.
If you “know” English- you know this is not a proper sentence. It contains what is known as an ambiguous antecedent. In English composition these phrases are to be avoided. A pronoun like “he” or “she” refers to something- a person usually. That thing is known as the “antecedent.” The pronoun doesn’t specify who it refers to, that is contextual. The speaker of this sentence would be displaying poor communication or grasp of language. Native speakers, even those who know well not to do this, can easily accidentally do so if they aren’t actively composing their words. If I say “she” and the antecedent is named “Alex,” then Alex is a female. If I say “he,” we know Alex is a male. So this is like if I said: “I love my sister. He is so great.” It’s technically a sentence- in English, and a listener could figure out what I meant or ask- but it’s still not a proper use of the language. A listener would likely use context or ask for clarification with such a sentence.
@guest makes a valid point. But- one might answer either:
“I want pizza”
Or
“I do not want pizza.”
By speaking in affirmative language you avoid ambiguity, and the trap of the double+ negative. Likewise- phrasing the question as: “Do you want pizza?” Uses affirmative language for less ambiguous communication.
“I want pizza”
Or
“I do not want pizza.”
By speaking in affirmative language you avoid ambiguity, and the trap of the double+ negative. Likewise- phrasing the question as: “Do you want pizza?” Uses affirmative language for less ambiguous communication.