I understand that Monica probably senses danger and wants to use her influence in a way she considers beneficial and urgently required (from her POV). However and as pointed out by several people already: Doing it this way is highly risky, prone to making relations worse, and even burn chastity as a whole.
She would do way better if she started with empathy and a belt for her self. If she could not resist ordering a belt for her daughter at this stage already, she could at least order both belts simultaneously. (And put her daughter's in a closet for the time being.)
This allowed self-experience and to get in touch, maybe by self-locking / time-based locking until a dedicated keyholder is found. While on the same hand working on the relationship to her daughter, in the meantime. This way would have improved the chances to convey chastity and protection as something positive, substantially.
Rude, "panic chastity" measures have marred too many peoples' attitude, already. Monica woud be well advised if she could refrain from that. For her own and her daughter's long-term good.