
Quoting
pg1067
Personal representative for what purpose(s)?
These two statements seem to be in direct conflict.
Hypothetically, thousands of things could conceivably happen. If, prior to the date of the hearing, your mother moves out of the country, you would be obligated to disclose that to the court, and the court might decline to enter a guardianship order. This is something you ought to be discussing with your attorney.
I'm not sure what you mean by "legal grounds to demand."
If I were you, I'd talk with my attorney about seeking an emergency restraining order preventing your mother from leaving -- and preventing your brother from assisting her to leave -- the state until the guardianship hearing.