Is it permissible for a mother to demand the return of money she gave her son as assistance or a gift?

The money your mother gave you is a gift and you are not obliged to return it to her, because you have spent it. Ibn Abi Zayd al-Maliki mentioned that a father and mother can reclaim a gift from their child as long as the child has not married, incurred debt, or made any changes to the gift that would decrease or increase its value. Nevertheless, you must honor your mother and maintain ties with her through financial support, even if she is not in need, based on the Almighty's saying: "And We have enjoined upon man [care] for his parents. His mother carried him with hardship and gave birth to him with hardship," and the Prophet, peace be upon him, said: "Your mother, then your mother, then your mother, then your father."