It's abusive controlling behaviour. You may be under the age of 18 but you are also at university, living alone (or with flatmates), in college accommodation and mostly managing your own finances (either by SFE loan, part-time work, both etc). You are entitled to your own personal privacy.
"The use of hidden cameras is generally permitted under UK law,
if used in a legal manner and towards legitimate ends. Individuals may use covert surveillance
in their own home to spy on others, in the workplace to monitor employees, outside of a domestic or commercial property
for security purposes. There are a number of laws under the
Data Protection Act and Human Rights Acts that may impact on the use of hidden cameras.
In any type of covert surveillance, footage should only be used for the purpose for which it has been taken, which must be a
legitimate security reason. The person in possession of the footage is
responsible for its use, and
must only retain footage for as long as it is reasonably needed. It is
not permitted to release footage to third parties except when there is a legal necessity.
It is
illegal under UK law to deploy covert cameras in areas where individuals would have an expectation of privacy, such as bathrooms, changing rooms and locker rooms, or
plant a hidden camera in someone else’s home, or an area someone else owns."
The owner of the accommodation is the University. It is University property. The University is allowed to have safety devices in the room (fire/smoke alarm) and CCTV in hallways, kitchen and outside areas (as this is for a valid security and safety purpose). They are not allowed to have security cameras in places where people could be reasonably anticipated to get changed/undress such as in dorms, bedrooms or in bathrooms.
If they break this law, they run into an invasion of privacy, ownership of illicit materials and because the OP is a minor by law (age 17), they could be charged with possession of child pornography (a serious crime). Because of all of these which would heavily damage a University's reputation (potentially resulting in a court case) and damage the welfare of the individual, it is extremely unlikely they would allow any such cameras to be installed or maintained in a dorm. Even if the camera belongs to the mother if it is used in University property the University could be held liable by proxy for allowing its use.
On the side of the mother, it is not allowed to plant a hidden camera in someone else's home or property and as the property is University-owned, that law would apply in this case. So in short, no, it is not allowed. If this were happening in her own house that would be a different case and less questionable (although still manipulative and controlling, nevertheless).
If a cleaner or maintenance worker enters the room, spots a camera that is suspicious (ie a hidden camera, or a camera that does not look like a personal camera) they may report it. Most likely they would report and then dismantle it unless they suspected a bigger child welfare/abuse issue, but why would you take that chance over a camera.
edit: as
Nmys also pointed out, if someone else enters the room they haven't given consent to be recorded and so the owner of the footage (the mother in this case) would be liable under UK privacy laws.