What is the ruling of the Shari'ah on demanding money that was stolen after it had been sent to another person with the authorization of the owner of the money, knowing in advance that she would bear responsibility?

If a loan is made in a specific currency, it is not permissible to agree to repay it in another currency. This is because such an agreement is considered currency exchange (sarf), which requires immediate mutual possession (qabdh) in the same session of the contract, based on the Prophet Muhammad's (peace be upon him) saying: "Gold for gold, silver for silver... like for like, equal for equal, hand to hand. If these types differ, then sell as you wish, provided it is hand to hand."

Therefore, the amount must be repaid in the same currency in which it was borrowed.

As for the money being stolen from your agent, your liability is not discharged until the money reaches its owner, because your agent is considered your messenger in delivering the money.