Can a guardian in Missouri keep my Aunt from seeing my dying mother?

Her current guardian is dieing of cancer and won't let her leave her house, she's a prisoner. She wouldn't have groceries if I didn't look out for her. My mom is dieing and asks for my Aunt.

Your aunt already has a Guardian? If she does, she cannot make decisions for herself. If her Guardian is dying, then petitioning for a new Guardian is totally appropriate.
As far as getting her to go out and visit someone, the Guardian decides whether she is physically and mentally well enough to go. I do not take my sister to see the sick or go to wakes. She would be distraught for days.