Is it permissible for me to donate the value of the bag and its contents as compensation for not sending it to a former maid, considering the circumstances mentioned and the current unavailability of a means to contact her?

Destroying a maid's belongings or disposing of them without her permission is an act of aggression. You must guarantee what you have destroyed by delivering its value to her. If that is not possible, then donate it as charity, while guaranteeing her right if she demands it. It is not permissible to take control of her belongings by accusing her of theft without clear proof.