Edit: I started writing this before your reply and only saw it after I posted it.
It's not entirely clear to me from your post what you are trying to do. Do you want your final attribute to be "Boy_B_rig_v001"? Because then the reply above will work. However, it seems more likely to me that you would want to extract the useful name from each object such as "body". If that is the case here are some things you can do.
If your path is
/blah/blah../blah/Boy_B_rig_v001:body_SUBD/Boy_B_rig_v001:body_SUBDShape
and you want a name attribute
then you can use a Muscle ID SOP with the Attribute Name set to `name` , Initialize from Input Attribute Toggled on, and Element Pos fom End set to 1. This will extract the second to last entry in the path attribute and store it as a name attribute.

If you wanted to clean the namespace from the name then you can use an Attribute String Edit SOP. Specify `name` in the Primitives field, and then it the Editor tab, in the From field put "Boy_B_rig_v001:*", and in To put "*". If you also wanted to remove the "_SUBD" you can instead put "Boy_B_rig_v001:*_SUBD" in the From field.

If you want your name to overwrite your path attribute, then you can use an Attribute Rename SOP, go to the Primitive tab, specify your From/To attributes, and toggle on Overwrite Existing Attributes.

Hope that answers your question!