A:
It is Wajib (obligatory) on a person to obey his parents when they command him to do a Ma`ruf (that which is judged as good, beneficial, or fitting by Islamic law and Muslims of sound intellect). Allah (Exalted be He) says,
And your Lord has decreed that you worship none but Him. And that you be dutiful to your parents. If one of them or both of them attain old age in your life, say not to them a word of disrespect, nor shout at them but address them in terms of honour.
Accordingly, it is Wajib on you to greet your father and to help him with his affairs as your mother commands you to do. On the other hand, your mother has to endure with patience all the difficulties that face her. She has to do so for the sake of Allah (Exalted be He) for it may be that Allah (Exalted be He) removes her hardship. She has also to be kind to her husband and do as much Ma`ruf to him as she can. Allah (Exalted be He) says,
...certainly We shall not make the reward of anyone who does his (righteous) deeds in the most perfect manner to be lost.
And,
And the good end (i.e. Paradise) is for the Muttaqûn (the pious).
We pray that Allah (Exalted be He) helps you to be dutiful to your parents (Part No. 25; Page No. 152) and to guide your parents to be kind to each other.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.