Would the deeds of the maternal aunt who quarreled with her siblings and they died upon that be accepted, and is there any repentance for her?

If the aunt abandoned her sisters and brothers, she committed a grave sin, and she is in danger if she does not repent. The Prophet, peace and blessings be upon him, said: "It is not lawful for a man to abandon his brother for more than three nights, meeting each other and one turning away and the other turning away. The better of them is the one who initiates the greeting of peace." And his saying: "It is not lawful for a Muslim to abandon his brother for more than three [days]. So whoever abandons for more than three [days] and dies, he will enter the Fire."

The sister's crying and regret after death will not benefit her; rather, it would have been more appropriate for her to rectify the matter before that. She should learn from what happened and refrain from abandoning her brother.

Her repentance is accepted with its conditions, as long as it does not reach the ghargharah (approaching death). And nothing was mentioned to indicate the non-acceptance of her good deeds.