A private company court appointed my mother's great niece. She was not interested but was chosen because as only son I was hospitalized. What can I do?

I read this to be that the great niece is the guardian, but did not want to be and "they'( niece,, family ?) are stealing the money?

So...

You were in hospital.
Your mother's great niece was not willing to act for your mother.
So the court appointed a professional company to operate guardianship for your mother?

And now you are taking care of your mother full-time, and alarmed to see her funds being spent in fees payable to the court-appointed guardian?

Are you now in a position to take on the guardianship, if you can get the court to revise its earlier order? I don't know, but it may be possible to ask for that.

Also, sorry I can't quite figure this out - you ARE okay for money for yourself, or you're not because you've had to give up your job?