Is it permissible to return the remaining amount after the renovation to the tenant of the new rental apartment only, given that the cost of renovations was supposed to be divided among the old residents only, but the cost was distributed among the old residents and another new rental apartment?

The old (open-ended) rental contract must be terminated, and the apartment returned to its owner. A tenant who refuses to do so is considered a usurper. The tenant is not obligated to participate in the renovation of the house; rather, the landlord is, and he must provide suitable housing until the end of the contract. It is not permissible to stipulate that the tenant is responsible for maintaining the property. As for the tenant with a void contract, it is permissible to take the cost of renovation from him if he owes money that the landlord has not forgiven, and the amount taken does not exceed what he owes.