Among the options, the sentence that matches pronouns and antecedents correctly is:
C. My husband surprised me with a dozen roses on our anniversary.
An antecedent is the noun to which a pronoun refers. The pronoun substitutes the noun, so the two words must match when it comes to number and person of speech.
For example, if you are talking about a woman named Elizabeth, you should not use "it" or "he". The correct pronouns should be "she", "her", and "hers".
Letter A is incorrect because it uses the pronoun "she" to refer to the flower. The correct pronoun is "it".
Letter B is also incorrect because it uses "their" to talk about the cake. The correct pronoun is "its".
Letter C is the only correct option. It uses "our" to refer to the the speaker and her husband.
Letter D is incorrect, because it uses "it" to refer to the plural noun "flowers". It should use "them".