Rubina was invited her friends . . . . . . . . dinner.

The question asks which preposition best fits the sentence to show Rubina invited her friends to a dinner.

Let's look at each option:

Option A: over - "Over" usually means something is above or across something else. It doesn't make sense here.

Option B: with - "With" means together. While Rubina was *with* her friends, it doesn't show she invited them to dinner. It suggests they were already together.

Option C: to - "To" indicates direction or purpose. "Invited to dinner" is a common and correct phrase. It means Rubina invited her friends to attend the dinner.

Option D: for - "For" can mean in behalf of or to benefit someone. While she might have prepared dinner *for* her friends, it doesn't mean she invited them.

Therefore, the correct answer is Option C: to because it accurately shows that Rubina invited her friends to the dinner.