What do you do about your mother's urgent desire to marry you off and your rejection of that, and your desire to travel to Palestine to help?

Marriage is better for those who are capable of it, and obedience to one's mother is obligatory in what is good, while disobeying her is an act of undutifulness. If marriage is obligatory or recommended for you, then you must obey your mother in her request for you to marry. Otherwise, there is no obedience in defying the Sacred Law. Similarly, traveling to Palestine does not contradict your mother's desire for you to marry.