Beneficiaries are asking for details of a bank account that was held jointly with rights of survivorship. Not with them. It passed directly upon death, as such, did not go through probate. All holdings were POD or joint w/right of survivorship. They received all of their POD monies directly from financial institutions.
Only money handled by executor Or listed on probate was from sale of home. Money from sale dispersed according to will.
They can ask but there is no reason that they should expect an answer.
An account held joint with right of survivorship passes to the survivor on presentation of the death certificate. Absent a suit for elder exploitation, no one else ever had any right to the money or any right to inquire about it either before or after the date of death.