Is zakat obligatory on money that has been held for 18 years by the حسب Council, knowing that it started below the nisab and exceeded it with profits, and how is it calculated and disbursed?

The guardian or trustee is responsible for the zakat on an orphan's money. If the aforementioned council is entrusted with the guardianship of orphans' money by the ruler, then it is responsible for its zakat. If it has already paid the zakat, there is no issue. But if it has not paid it throughout the period of guardianship, then it must pay the zakat for that period. As for profits resulting from usurious interest, zakat is not obligatory on them, and the orphans must dispose of them upon reaching maturity.