What's the oldest age people can get neuroblastoma?

Any age. While neuroblastoma is typically a disease of younger children, even infants, it can occur in adults. I have personally treated patients who were diagnosed in their 20s and there is a report of a 77-year old in japan who was diagnosed wtih this type of cancer.
Variable. There anecdotal cases of neuronal storms in adults even though it is primarily a disease of childhood.