The word "candidly" means to speak openly, honestly, and without reservation. It implies expressing one's thoughts or opinions straightforwardly and sincerely. 

Similarly, the word "frankly" carries a similar meaning of speaking honestly and openly.

In this context, Ngozi is having an open and honest conversation with her father about her proposed marriage.

Therefore, "frankly" is the option that best captures the meaning of "candidly" in this sentence.