Is the housemaid entitled to claim the remaining six salaries, given that the agreement was to hand them over to her upon her return to work? And is it permissible to deduct the costs of the new contract, the return ticket, and the wages of the temporary housemaid if these salaries must be paid?

If the employee completes his work, he is entitled to his full wage, and it is not permissible for the employer to withhold it from him or suspend it on a new condition; because of Allah’s severe warning to whoever takes full work from an employee but does not give him his wage. Consequently, it is not permissible to withhold the maid's due wages, and her return or non-return has no bearing on her entitlement to previous wages.

If the new agreement was made under duress, it is not permissible to deduct the amounts she lost. However, if it was with her full consent, then you have the right to deduct the cost of the contract, the return ticket, and the passport renewal. Deducting anything from her previous salary to hire a temporary maid is not permissible.