Is it permissible to work as a cleaner in a company that deals with gambling, fearing that the earnings might be unlawful, especially since there is a need to cover the mother's medical expenses, and can one rely on another profession that might not meet the need?

It is not permissible to work for companies that engage in forbidden activities, such as gambling, in accordance with the Almighty's saying: (And do not cooperate in sin and aggression. And fear Allah; indeed, Allah is severe in penalty). You must leave this job, and whoever gives up something for the sake of Allah, Allah will compensate him with something better. And the Almighty's saying: (And whoever fears Allah - He will make for him a way out And will provide for him from where he does not expect).