C. Was
It says "my parents or my older sister". The last subject stated is "my older sister" which is singular. And the only choice that's singular is 'was'. So that should be the answer.
The correct answer to your question is D. she will continue to help the guerillas
Usually, in a conclusion, you wrap up what you have been writing about the whole time. So, a conclusion is basically a summary of the whole text. You can introduce new ideas for the reader, but it is usually inadvisable. In a couple of sentences, you should finish your text, referring to the previous paragraphs and just wrap it all up nicely.
The way the author makes the story is what actually affects all of that
