What is the ruling on purchasing a house in installments and registering it in the wife's name out of honor for her, and do the wife's family (her mother, brothers, and sisters) inherit the house along with the children in the event of her death, given that the father is deceased?

There is no harm in buying a house and gifting it to the wife.

If the heirs are exclusively the husband, the mother, and the children, then the inheritance belongs to them, and the siblings receive nothing, as they are completely excluded by the presence of a male child.

The husband receives one-fourth due to the presence of a lineal descendant, and the mother receives one-sixth due to the presence of a child. The remainder goes to the children by way of ta’sib (residuary heirship), with the male receiving the share of two females.

It is not advisable to inquire about inheritances before the death of the deceased, as it is unknown who will die first, and the heirs or those excluded cannot be determined.