What is the ruling on abandoning one's mother due to her constant ill-conduct and the children's discomfort with living with her? And is speaking with a suitor over the phone considered haram?

The mother has no guardianship (wilayah) over the marriage of her daughter. Guardianship belongs to the male 'asabah (agnates), starting with the father, then the paternal grandfather, then the son, then the brothers, then the paternal uncles. If the suitor is suitable (kufū'), the guardians do not have the right to prevent her marriage to him. The girl has the right to present the matter to the judge to have him marry her or order her guardian to do so. The brother is not obliged to obey his mother in preventing his sister from marrying without a valid reason, because obedience to parents is not required in matters that harm the child. However, it is not permissible to abandon the mother or treat her badly, as her right to dutifulness is immense, even if she is neglectful. A girl speaking to her suitor is permissible to the extent of need and safety from fitna (temptation), and it is better for the suitor to speak with the woman's guardians.