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.
There is no doubt that raising your voice at your parents and fighting with them is an act of undutifulness to them and you are obligated to immediately take the initiative to repent from it because being undutiful to the parents is a grave major sin; so please refer to Fatwa 87856. Also, for more benefit, refer to Fataawa 88120, 84521 and 82254.
On the other hand, you did well by being keen on advising your parents and wishing good for them, but advice should be given in a gentle and good manner so that it can yield its fruits. Allaah Says (what means): {Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best.}[Quran 16:125] Moreover, it is confirmed that the Prophet said: “Indeed, Allaah is Kind and He likes kindness, and He confers upon kindness which He does not confer upon severity.” This is even more confirmed with the parents.
Moreover, being angry does not excuse a person (for being harsh to his parents), and there are some steps in the Sharee’ah for treating anger which we clarified in Fatwa 86681.
Besides, abandoning the prayer or being negligent about it makes a person in a very serious situation, so you should continue advising your mother about it, and we advise you to supplicate Allaah to guide her and to enable her to repent; you may seek the help of some scholars or knowledgeable people in this regard.
On the other hand, it is not permissible to prevent anyone from his share in the inheritance. So, if your maternal aunt has a share in the inheritance and she asks for it, then it is an obligation to give it to her and not deprive her from it without a sound reason, otherwise it is injustice to her. However, she has no right to ask for more than her share and it is not an obligation to give her this surplus unless (all) the other heirs approve of it.
As far as you are concerned, you should endeavor, as much as you can, to enjoin good and forbid evil and clarify the truth to whoever does not know it among your relatives and tell them the consequences of injustice without raising your voice at your parents and without making them angry. If they accept, then praise be to Allaah, otherwise you would have done what you are required to do.
Allaah Knows best.