"Lock her inside of her bedroom. Place guards below her window and at her door. Regina is not allowed to have visitors without my permission. Her food will be taken to her bedroom by you," Minnie gave orders to Duncan.
The trust Regina mentioned between them was nonexistent. Minnie stopped trusting Regina from the moment she allowed Aurora to leave and hit her own brother over the head. Still, she was going to play nice while she had Gilbert get the witches to wipe Regina's memories and to see if they recognized her as a witch.
Minnie needed Regina to reach her full potential if she was showing signs of being a witch. She would give Regina the one thing she wanted these days, which was to inherit the house.