How can one deal with parental disobedience and mutual insults at an advanced age, especially when the children feel guilty after their reactions?

One must repent to Allah Almighty by regretting the neglect of the parents' rights, ceasing their disobedience, and resolving not to return to it. One should also seek their forgiveness, humble oneself before them, frequently supplicate for them, and show remorse, while being careful not to provoke their anger. Allah Almighty says: (And your Lord has decreed that you shall not worship except Him, and to parents, be good.) The Prophet, peace and blessings be upon him, said: "The Lord's pleasure is in the parents' pleasure, and the Lord's displeasure is in the parents' displeasure," and "A disobedient child will not enter Paradise," and "Then cling to her, for Paradise is beneath her feet."