I'm not sure about number 1. Maybe: It was the happiest event.
2. The judge cautiously handed down her decision.
3. Mr. Majors was pressed hard to find an answer.
C - Beautiful antique instruments renames guitars
Appositives are nouns or noun phrases that renames another noun beside it. The phrase 'beautiful antique instruments' renames and is right beside 'guitars' as it is describing them.
