Assalaamu alaykum. Please calculate the inheritance according to the following information:
- Does the deceased have male relatives who are entitled to inherit: (A son) Number 2 (A husband)
- Does the deceased have female relatives who are entitled to inherit : (A daughter) Number 2
- Additional information: Mother had a house and gave a power of attorney to the younger brother, for tax purposes basically, but he sold the house and bought a new one in his name with his wife as beneficiary. He did inform us that he was selling the house, but now that mother is dead, he is unwilling to sell the house and give every one his due Shariah share.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ʻalayhi wa sallam, is His slave and Messenger.

If a woman passed away and left a husband, two sons, and two daughters, and no other heirs entitled to inherit except them – like a father, a mother, a grandfather, or a grandmother – then the estate should be divided as follows:

Her husband gets one fourth of the estate as a fixed share because she has descendants (children) entitled to inherit. Allah, the Exalted, says (what means): {But if they have a child, for you is one fourth of what they leave, after any bequest they (may have) made or debt.} [Quran 4:12]

The remainder should be divided among her children by virtue of Taʻseeb (having a paternal relationship with the deceased and not having an allotted share, so they get what is left after the allotted shares have been distributed). The male gets double the share of the female; Allah, the Exalted, says (what means): {Allah instructs you concerning your children (i.e. their portions of inheritance): for the male, what is equal to the share of two females.} [Quran 4:11]

Hence, the estate should be divided into eight shares: the husband gets one fourth (two shares), each son gets two shares, and each daughter gets one share.

As for the son's action of selling the house without the permission of the deceased, buying another house, and registering it under his name, then you should raise this matter to the Shariah court.

Allah knows best.