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.
Answer: A: My sister is excited that her swim team earned a championship and that her debate team won its first tournament.
Explanation: In this sentence the common word "that" is used ("that her swim team" and "that her debate team") leading me to believe that A is the answer.