How can someone who took money from a company that was a three-person partnership, and then closed, return the money to its owners without revealing her identity, especially since she does not know the exact amount of the sum and her financial situation is difficult?

The money taken from the company must be returned to its owners, even through indirect means. If it is difficult to ascertain their shares, someone can be appointed to inquire on their behalf. If some of them cannot be reached, their share should be given in charity. Then, if they are found, they are given the choice between approving the charity or reclaiming their money. It is permissible to pay the amount in installments if it cannot be returned in a single payment. If returning the money conflicts with repaying a due loan, prioritizing the repayment of the money is preferred if the loan can be postponed without harm. Otherwise, repentance suffices, and the money should be repaid after the loan is settled. This is based on Allah's saying: "Indeed, Allah commands you to render trusts to whom they are due" and "So fear Allah as much as you are able," and the Prophet's (peace be upon him) saying: "On the hand is what it took until it returns it."