Can old people hear better than young people?

No.
Older people, mostly those who would be classed as elderly, gradually experience a decline in their hearing levels. Over the years, the ears begin to get damaged from loud noises, physical knocks to the head and so on. A child with less of these would have better hearing.

It has also been proven that youngsters can hear a certain frequency of sound that adults cannot. This has led to shops in the UK putting an "amplifier" outside their shop door which emits a small sound that only youngsters can hear - the purpose is to prevent youngsters from standing around outside the shop, putting off customers. The sound doesn't affect older people because they cannot hear it.

So your answer is no.
No.
Older people, mostly those who would be classed as elderly, gradually experience a decline in their hearing levels. Over the years, the ears begin to get damaged from loud noises, physical knocks to the head and so on. A child with less of these would have better hearing.

It has also been proven that youngsters can hear a certain frequency of sound that adults cannot. This has led to shops in the UK putting an "amplifier" outside their shop door which emits a small sound that only youngsters can hear - the purpose is to prevent youngsters from standing around outside the shop, putting off customers. The sound doesn't affect older people because they cannot hear it.

So your answer is no.