All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Hajj is an immediate obligation according to the most preponderant opinion and it is the view of the majority of the jurists . We have already clarified this with evidence in Fatwa 91223, so please refer to it.
Therefore, if you and your wife have the financial and physical ability, then you are both obligated to go for Hajj before helping others to do so.
However, if both of you do not have the financial ability and your wife wants to help her parents from her own money so that they would go for Hajj, then she is permitted to do so, and this is an act of kindness and obedience toward her parents and this is one of the great deeds that bring you closer to Allaah. However, your wife is not permitted to force you to help her parents from your own money, and you are not obligated to help them. But if you do so, it is a good act that leads to more affection between you and your wife and between you and your in-laws. Also, it is permissible for your parents-in-law to go for Hajj with the money that you donate for them.
The following matters should be mentioned:
1- A Muslim is not obliged to endeavor to earn money in order to perform Hajj because the ability is a reason for the obligation of performing Hajj on the person, and a Muslim, in case the reason of the obligation is lacking, is not required to gain it, as established in the principles of Fiqh; for more benefit, please refer to Fatwa 82631.
2- It is good for a Muslim to endeavor to leave his family rich after his death as the Prophet said Sa’d Ibn Abu Waqaas : ''It is better to leave your heirs rich rather than to leave them poor, begging from people." [Al-Bukhari and Muslim]
However, it is dispraised to fear and be worried about the future as Allaah took the responsibility of providing for every creature; Allaah Says (what means): {And there is no creature on earth but that upon Allaah is its provision.} [Quran 11:6]
Moreover, the Prophet said: ''Jibreel (Gabriel) inspired in my heart that no soul will die until it would have consumed its (designated) provision, so seek your provision in moderation." [At-Haakim – Al Albaani graded it Saheeh (sound)]
Allaah Knows best.