Is it permissible for two daughters to sell the piece of land that their father gifted to them when they were young, knowing that he used to work in a usurious bank and has passed away?

If the two daughters know that the land was acquired unlawfully (haram), it is not permissible for them to benefit from it. They must donate its price to charitable works to dispose of it, unless they are poor, in which case it is permissible for them to benefit from it as charity, not as inheritance. This applies if it was purely from unlawful wealth. However, if it was from lawful wealth, then it is permissible. If lawful and unlawful wealth are mixed, the preponderant opinion is that it is permissible for them.