Will the wife's charity on behalf of her deceased husband be counted and reach him, even though she did not intend it for herself or his heirs, but rather intended it purely for him?

If you intend for the charity to be from your own money and you donate its reward to your husband, this is permissible and you will be rewarded for it, and it is hoped that its reward will reach him. As for the money you took from your husband's wealth during his lifetime and without his knowledge, it must be returned to the heirs. The wife's maintenance varies according to common custom, as Allah the Almighty said: (And live with them honorably) and (A reasonable provision).