Is postponing travel to please one's parents considered hypocrisy, and does it involve injustice to one's wife and daughter, especially given the better financial return abroad and the difficulty of family reunification for a period?

There is no blame upon you for foregoing travel to please your parents and consider their feelings. You will be rewarded for it, Allah willing, because it is an act of dutifulness (birr). It is not showing off (riya') as long as you did not do it with the intention of showing off. You are not obligated to travel to earn a higher salary as long as you are able to provide for your wife and children with your current salary. Your decision not to travel does not constitute injustice to them.