Is it permissible for a woman suffering from kidney failure and her husband suffering from diabetes to perform Hajj, knowing that the husband's mother has not performed Hajj and she is old, ill, and resides in Morocco?

Hajj and 'Umrah are obligatory only upon those who are capable both financially and physically. If one is incapable financially and physically, or financially only, then there is no obligation upon him. However, if one is incapable physically only (due to old age or a chronic illness from which there is no hope of recovery), then he must appoint someone to perform it on his behalf (istinaabah). Whoever is able to go himself is obligated to do so, based on the Almighty's saying: "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) for it," and the hadith of Ibn 'Abbas regarding appointing someone on behalf of an elderly person.