Is it permissible for an employee to take the sums granted by the company as a meal allowance, knowing that he does not benefit from the accommodation, for which 10 dinars are deducted from his salary monthly?

The rent you pay for the room is obligatory upon you, whether you inhabit it or not, because the mere signing of the lease agreement makes the rent due. If the room's rent is obligatory upon you, it has no relation to the meal allowance that the company pays you. You are permitted to take this allowance if you are entitled to it according to the contract concluded between you and the company; otherwise, you are not permitted to take it, and you must return it.