Praise be to Allah.
Hajj is one of the obligatory duties of Islam, one of the pillars of Islam. It is not permissible for the person who is able to do it to delay it or to hesitate to do it. And there is no obedience to any created being if it entails disobedience to Allah.
Allah says (interpretation of the meaning):
“And Hajj (pilgrimage to Makkah) to the House (Ka‘bah) is a duty that mankind owes to Allah, those who can afford the expenses (for one’s conveyance, provision and residence)” [Aal ‘Imraan 3:97]
The Prophet (peace and blessings of Allah be upon him) said: “Islam is built on five (pillars): testimony that there is no god except Allah and that Muhammad is the Messenger of Allah, establishing regular prayer (salaah), paying the zakaah, fasting in Ramadaan, and pilgrimage to the House.”
So it is not permissible foryou to please your mother by disobeying Allah. You should honour her and treat her with kindness, but not by disobeying Allah. Whoever pleases people by angering Allah, Allah will be angry with him and will make people angry with him.