Align roll relative to the axis defined by the bone and its parent. X, Z. Global Axis. Align roll to global X, Y, Z axis. X, Y, Z. Active Bone. Follow the rotation of the active bone. View Axis. Set the roll to align with the viewport. Cursor. Set the roll towards the 3D cursor. Flip Axis. Reverse the axis direction. Shortest Rotation
Properties - Parenting — Blender Manual
You can parent an object to a specific bone using a 'Child Of' constraint:
Here, the object I want to parent to an individual bone has a 'Child Of' constraint added, with the armature and bone I want it to follow selected from the 'Target' and 'Bone' search boxes.
Pressing the 'Set Inverse' button may be required to return the object to it's original position as after choosing the target object it may jump to that bone's position.
