C

Step 1: In a streamline flow, the flow of fluid particles is smooth and orderly, following paths called streamlines. As it flows, the fluid maintains a constant flow pattern.
Step 2: In streamline flow, fluid velocity can vary from one streamline to another but remains constant at a given point along the same streamline.
Step 3: The speed of individual particles can change, hence option A is incorrect. The velocity, which includes direction, can follow different streamlines or vary in magnitude, making option B incorrect.
Step 4: However, the kinetic energy ($KE$) of the particles arriving at a given point in a streamline, where they come from different streamlines assuming incompressibility and no viscous effects, will be the same due to conservation of energy principles. Therefore, option C is correct.
Step 5: Option D regarding moments (which is angular momentum) is contextually irrelevant in basic streamline flow analysis without specific angular context, thus making it incorrect.
Therefore, the correct answer is C.