Who inherits the contents of the apartment that the husband alone established, knowing that the husband, wife, and their children all died in one accident, and the husband has two brothers, and the wife has a mother, a brother, and three sisters' daughters, and the husband's brothers paid the apartment's rent for two years after his death?

If two or more inheritors die in a common calamity such as a building collapse, drowning, or fire, and it is not known who died first, then none of the deceased inherits from the other. The wealth of each of them is distributed among their living heirs, because one of the conditions for inheritance is the ascertainment of the heir's life after the death of the deceased, and this condition is not met here.

Accordingly, in the aforementioned car accident, each deceased person is considered a stranger to the other, and the wealth of each of them belongs to their living heirs, not to those who died with them in the accident.

Thus, the two brothers receive what their brother (the husband) left, equally. The mother receives one-sixth of what the wife left, and the brother and three sisters receive the remainder, with the male receiving the share of two females.

As for the contents of the apartment, if it is proven that the husband furnished it, then the furniture belongs to his heirs. If there is no evidence, then what is suitable for men belongs to the husband's heirs, what is suitable for women belongs to the wife's heirs, and what is suitable for both of them is divided equally between their heirs.

Finally, matters of inheritance are complex and require مراجعه (review by) the Sharia courts to ensure the full application of Islamic rulings.