What is the ruling on the money remaining from the accommodation or transportation allowance that an employee has saved?

Look into the money the company pays the employee. If it is exclusively for transportation and accommodation, such that the employee is authorized to pay these expenses on the condition that any remainder is returned, then any amount exceeding the customary expenditure must be returned to the company. However, if it is paid as a lump sum for the employee to manage their affairs, and no remainder is to be returned, then the employee may benefit from any surplus money they have from this amount.