A pronoun must refer to a specific antecedent, not to a word that is implied but not present in the sentence.
The pronoun them referred to Ann’s braids (implied by the term braiding), but the word braids did not appear in the sentence.
Modifiers, such as possessives, cannot serve as antecedents. A modifier may strongly imply the noun that the pronoun might logically refer to, but it is not itself that noun.
The pronoun she cannot refer logically to the possessive modifier Mary Gordon’s. The revisions substitute the noun Mary Gordon for the pronoun she, thereby eliminating the problem.
Exercises:
Pronoun reference 1
Pronoun reference 2
Pronoun reference 3
Pronoun reference 4