(T.O.K)To what extent does money brings happiness? To what extent does money brings happiness?

That is not a good TOK topic, because it about metaphysics, not epistemology. TOK is about epistemology.

TOK is about HOW we come to think what we think, in other words, what 'road of logic' must you travel to get from an idea to a belief. The idea that money makes happiness is about the value of money and of happiness, not about the road of logic required to believe that.

For example, it was John Locke's idea that "All the objects of the understanding are described as ideas, and ideas are spoken of as being in the mind (Intro. 2; Bk. 2:1:5; Bk. 2:8:8). Locke’s first problem, therefore, is to trace the origin and history of ideas, and the ways in which the understanding operates upon them, in order that he may be able to see what knowledge is and how far it reaches." http://www.iep.utm.edu/locke/#SSH2a.i

It was Kant's idea that we have a priori and a posteriori knowledge. These things are what are meant by TOK.

Need to be fulfilled by the value system which brings pleasure but not happiness.

It only brings happiness to those that only ask the question once...