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 ‘alayhi wa sallam, is His slave and Messenger.
After a person dies, all the property (money, gold, realty, land, and the like) they have owned becomes the estate of all the legal heirs. In addition, the legal heirs have the choice to either divide the property or keep it as it is and share its revenues according to the rules of inheritance stipulated in Sharia. Moreover, it isn`t permissible for any of the heirs to refrain from dividing the estate in case another heir claimed his/her share. However, heirs are allowed to divide the whole estate or part of it; either consensually or through Sharia court.
Claiming your (Asker) share of the estate isn`t considered an act of disobedience to your mother particularly since you are in a dire need for that share. On the contrary, your mother should facilitate the division of the estate and make sure that each heir gets their lawful share. Afterwards, she can ask her children to provide for her in case she didn`t have enough money to cover her basic needs.
In conclusion, it is permissible for a legal heir to claim his/her share of the estate and it isn`t permissible for another heir to ban him/her from that. Moreover, we advise all parties to resort to dialogue to solve this problem. However, if things got complicated and there was no room for consensual solution, then you can go to court. And Allah the Almighty knows best.