Is the person who replaced the former tenant in the accommodation entitled to recover the commission fee paid to the former tenant, after the decision to evict bachelors residing in the property, especially since the former tenant was not aware of this decision beforehand?

It is permissible for the tenant to take a sum of money from a second tenant in exchange for waiving their right to the usufruct of the leased property during the lease term. This amount is considered a "key money" (badl khuluw) and is Islamically permissible. The property owner does not have the right to terminate the lease before the agreed-upon term expires, because a lease is a binding contract. If the owner prevents the tenant from benefiting from the property for the remainder of the term, the owner is not entitled to rent. The amount that the questioner took in exchange for waiving their right to the usufruct of the housing does not obligate them to return it, unless they deceived or cheated the other party.