Identify the feminine form of the word: 

feminine appeal; feminine attire. possessing traits that are typically associated with women, such as tenderness or sensitivity. A man having an effeminate or womanising gait. staff members who identify as female or as being of the female sex.

Dukes is the plural form of the sword duke.

The word duchess is wrong. It has no meaning, and no such word exists in English.

A duchess is a female monarch of a duchy or a woman who bears the status of a duke in her own right. It also refers to a duke's wife.

Dukina is an erroneous word; there is no such thing.

Hence, the correct option is option  C.