Is it permissible for a wife to file a lawsuit for maintenance against her miserly husband, who lives with her, because he restricts her and her children in all necessities of life, despite his great wealth?

If the husband is well-off but refrains from spending on his wife and children in a reasonable manner, then the wife has the right to take from his money, without his knowledge, the amount of the reasonable expenditure. If she is unable to do so, she may refer him to the judge to compel him to provide for the maintenance.