Is the father accountable for working in a non-Islamic bank, buying shares from it and selling them after their price doubled, and buying a plot of land with the principal and profits?

Working in usurious banks and receiving a salary from them is forbidden, unless the services do not aid in usury, which is highly unlikely. It is also forbidden to buy shares from non-Islamic banks. As for land purchased with illicit money, its ownership is permissible, but one must dispose of the illicit money to the extent of its amount.