Thank you , So they need to declare even if they never used or brought that money into USA ?
If so , does this mean for last few years they are will be considered as no complaint with requirements ?
Mostly Fixed deposit (Like CD in USA) which will give interest after maturity. All the income in those accounts are earned in India when parents use to work and paid India tax as per requirements.
If they are not being claimed as dependents and their gross income from all sources was less than $24,400, assuming that they would file jointly, they would not need to file a tax return.