Is the son obligated to repay the loan of his deceased father who paid many times its value to the bank?

It is obligatory to pay off your father's debt from his inheritance only. Evading a creditor's debt in exchange for a previous usurious interest is a matter of scholarly disagreement. However, in the case of banks, it is not permissible to evade the debt because banks are legal entities whose ownership may change. Therefore, the loan must be paid to the bank from your father's inheritance to clear his liability. As for the interpretation of dreams, it is not within the scope of this website.