Is working with one's mother in managing an inheritance considered a stable job? How should one deal with a fiancée who fears financial dependence on the mother and dispel her concerns about the instability of this income? Is it better to seek another job to avoid sins in private companies?

If the mother is an agent for the heirs, she must act in the best interest of her principals. She is permitted to appoint someone to assist her if she is explicitly authorized to do so, or if the agency necessitates it. If her appointment of her son involves a wage, then for the validity of the ijarah (leasing/hiring contract), the wage must be known; otherwise, he is entitled to a fair market wage (ajrat al-mithl). The situation must be rectified for the ijarah to continue lawfully. As for the son's fiancée, she should not interfere in his work. If the son deems it beneficial to continue this lawful work, he should do so, for it is an act of filial piety towards his mother and falls under the fear of God (taqwa Allah) which facilitates provision.