2. "Did they have lunch at home?"

Решение:

Нужно преобразовать прямой вопрос в косвенный. Используем союз if.

1. Исходный вопрос: "Did they have lunch at home?"
2. Преобразуем в косвенный: They asked me if they had lunch at home.

Ответ: They asked me if they had lunch at home.