This is 3D vector problem.
You haven't provided enough information to solve this problem. Can you explain how the Yaw Pitch and Roll angles measured around these axes will tell you where "B" is? If "B" is purely dictated by an angle from these axes (Pitch Roll and Yaw), There will be a whole series of points along a straight line that satisfy this condition, so "B" will not be a single point. You also need a distance from A to B.
Imagine attaching a string to the bottom corner of a room (where 2 walls meet the floor, so this is like x, y, and z axes at point A), and attaching the other end to something in the room (like a tv or something). The angles between any point along the string (point B), and the corners of the room (the axes), stay exactly the same. This means you can pick any point along the string, and the Yaw, pitch, and roll from A to that point are equal. Therefore, point B is variable unless you have a distance from A as well.
Can you explain in more detail your problem please or provide more information?
Please visit Facebook and Private maths tuition UK, online maths tuition UK, GCSE maths tuition UK to support us