If you are from Africa, and you need to travel there for completing the essential paperwork, she can accompany you even though she is still in 'iddah. The Prophet (peace be upon him) allowed women in 'iddah to go and chat with their fellow sisters and spend as much time with them but come home for sleep. 'Aishah, the wife of the Prophet (peace be upon him), used to take out the widows from her family with her to perform 'umrah, and when she was asked about it, she said, "'iddah is a state of mind" in other words, as long as she avoids beatifications, she may do so.
In light of this, your mother can travel to her home country for the essential paperwork.