What is the ruling on the loss of the amount of money that a mother borrowed from her son in a fraudulent company, and her inability to return it, and how should the son deal with his mother in this situation?

If a mother has borrowed from her son, he has the right to demand repayment of the debt, according to the preponderant opinion of jurists. However, if she is in straitened circumstances, he should waive all or part of the debt for her, or grant her a reprieve until her situation eases. This is based on the Almighty's saying: "And if there is one in adversity, then [grant him] a reprieve until a time of ease. But to forgo it as charity is better for you, if you only knew," and on the Prophet's (peace be upon him) saying: "Whoever grants a reprieve to one in adversity or absolves him [of the debt], Allah will shelter him in His shade." The mother is more deserving of this because it is an act of filial piety towards her.