Is the mother sinful if she permits the installation of a shower on the roof of her building, which is leased to tenants, including her two brothers?

If it is highly probable that the tenants are using the device to watch obscene channels, they must be advised and informed of its impermissibility, and told that the contract will not be renewed if they do not stop. If they desist, then all is well. Otherwise, there is no sin upon the owner after giving advice, and she must not renew the contract.