All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
The share of your father in the house is the property of all the heirs after his death, and your mother is not permitted to prevent any of the heirs from taking his/her share in the inheritance if they wish to do so. If she prevents them from that, then she is disobedient to Allaah, and there is no obedience for her in this case, as the Prophet said, “There is no obedience to a creature in disobeying Allaah (the Creator).” [Ahmad - Shaykh Shuayb al-Arna'oot classified it as saheeh (sound)]
Therefore, you should clarify this matter to your mother, as well as the fact that she is not permitted to appropriate the shares of other heirs under any pretext, because this is a share that Allaah decreed for the heirs; Allaah says (what means): {For men is a share of what the parents and close relatives leave, and for women is a share of what the parents and close relatives leave, be it little or much - an obligatory share.} [Quran 4:7]
If you are gentle with your mother and show her these religious texts in a wise manner, we hope that she will abide by the Ruling of Allaah and accept it.
If she does not accept it, then there is no obedience to her as we have already mentioned, and she is only entitled to her legitimate share, which in this case is one-eighth due to the existence of the children (direct heirs).
Allaah knows best.