She has good…….over the famous foreign languages.

The correct option is command.

Let's understand the meaning and context of the options when used with the preposition 'over' in relation to languages and skills:
1. Command over: Having a "command over" a language or subject means possessing a thorough knowledge, mastery, or fluency in it. It is the idiomatic standard expression used when referring to language proficiency (e.g., "a good command over English/foreign languages").
2. Expertise: Generally followed by the preposition 'in' (e.g., "expertise in a field"), not 'over'.
3. Control: Usually refers to power, direction, or restraint over actions or situations, rather than linguistic mastery.
4. Authority: Refers to power, rights, or being an expert figure, but is not used in the context of skill fluency as "good authority over languages".

Therefore, the word command fits perfectly in the given sentence: "She has good command over the famous foreign languages."