Spirit rescue is the term used for moving a ghost or lost soul to a better place - normally to join the rest of their soul. If the incarnation that the soul came from has died then the lost fragment of soul will join it. If the soul is incarnate in another life, quite honestly, I don't know where it goes to but it is still looked after by the higher self (spirit). My feeling is that in both of these circumstances the lost soul gets healing and help to release its fears enough to rejoin the rest of the soul.
I have done many spirit rescues and they are done in a meditation during which healing is sent to the lost soul to help it to release its fears and prepare to be guided to a higher place. Spirit rescue is primarily an act of compassion and requires unconditional love to heal the lost soul. But another part of a spirit rescue is that the rescuer uses the will to persuade the lost soul to move on to a higher place. The lost soul has an element of free will and the amount of will that it has will depend upon the amount of solar plexus consciousness it has. If a lost soul chooses not to move on then many spirit rescuers may use their collective will to overcome that of the lost soul or it may be unmoved. If it very upset and has come from an old and great soul, a newer soul might have difficulty in doing a spirit rescue. If there are several spirit rescuers it might be easier. If the lost soul is influenced by other mischievous or unwise discarnate souls the spirit rescue may be more challenging or inadvisable. It should be borne in mind that even the smallest part of human consciousness is a divine creation and a divine being, however much fear or pain it temporarily has. All lost souls should be treated with reverence and respect.
Spirit rescue should generally only be done with the approval of spirit guides. They know exactly what is needed and the capability of the rescuer/s. Attempting a spirit rescue without or against divine approval is very unwise. Spirit rescue is always done with divine help and guidance since the spirit rescuer plays a relatively small part.