Давайте разберем каждое предложение, используя Present Continuous (настоящее длительное время).
1. My grandma (visit) people at the moment.
Утверждение: My grandma is visiting people at the moment.
Отрицание: My grandma is not visiting people at the moment.
Вопрос: Is my grandma visiting people at the moment?
Краткий ответ: Yes, she is. / No, she isn't.
2. The children (make) special lamps at Diwali.
Утверждение: The children are making special lamps at Diwali.
Отрицание: The children are not making special lamps at Diwali.
Вопрос: Are the children making special lamps at Diwali?
Краткий ответ: Yes, they are. / No, they aren't.
3. My dad and brother (exchange) gifts with each other.
Утверждение: My dad and brother are exchanging gifts with each other.
Отрицание: My dad and brother are not exchanging gifts with each other.
Вопрос: Are my dad and brother exchanging gifts with each other?
Краткий ответ: Yes, they are. / No, they aren't.
Таким образом, мы разобрали каждое предложение, применив правила использования Present Continuous.