Does the husband inherit from his wife the money in their joint safety deposit box, the exact share of which is unknown for each of them, and how is the inheritance to be divided?

The husband inherits half of his wife's wealth if she has no lineal descendant (children or grandchildren), or a quarter if she has a lineal descendant.

If the exact share for each of them is unknown, reconciliation is the optimal solution between the husband and his wife's heirs, based on what was narrated in the hadith of Umm Salama, that the Prophet (peace and blessings be upon him) said: "You refer your disputes to me, and I am only a human being. Perhaps some of you are more eloquent in presenting their arguments than others. I only rule between you based on what I hear. So, if I rule in favor of someone a portion of his brother's right, let him not take it, for I am only cutting off a piece of fire for him, which he will come with as a collar around his neck on the Day of Resurrection."

Some scholars have stated that reconciliation is what is appropriate for resolving disputes among relatives.