I Have a Question

I know somebody who lives with there mum who's ill and she has carers .and what not .she can't move about go out to do things her self her son has her bank details often takes money out and uses it to buy dvds and cds and vinyls he's on the ferge of been tested for austim but we don't know yet but he's took a lot of money coupe of hundred every few weeks or every month even tho he is in charge of the money and its her son do you think he has the rights to still take money like that.or do you not see a problem with it.