Can i ask, if who is the responsible to buy the...

As it was also explained to you if the work was terminated by the sponsor and the employer, and the work contract did not include paying the return ticket, so the return expenses will be on your personal account.
In other words, the issue is refunded to the work contract if it is stipulated or not, and if the contract stipulates the payment of the ticket, then the sponsor must provide it to you and your family.