On Earth, 100 years in the future, there is a global societal collapse when 95% of the population dies. During this time an organization emerges that aggressively gathers and guards technological knowledge.
They basically have all technology and means to produce it and actively stop others from doing the same. They have a network of informants and permanent bounties of people that possess technology or knowledge of it. For all practical purposes they are an invincible force and they will do whatever they can.
So to my question. How effective can they realistically be? In what technological stage can they keep the rest of the world? Can it be early industrial age or even earlier?
EDIT: The current time line is about 200 years after the collapse. We should also assume that until that point they are operating efficiently.
Also when I say organisation, I do not mean 20 people, I mean something like 200k.
EDIT2: What does restricting technology means:
Basically every technology that can be viewed as a threat. Mainly military technology. They are not viewing themselves as murderers but rather as keepers of the knowledge. Their official goal is to prevent an other collapse.
So they leave "primitive" technology free. Things like metallurgy, agriculture etc. to avoid an uprising.
They want a stable and operating society, just in a much lower technological level than theirs. So I was thinking something like medieval technology is mostly free.
I was wondering about things like "can they restrict the usage of gunpowder?" without being too extreme?