Upvote:3
First of all, Terminal 3 at DXB is HUGE but it is a friendly place. Directions up/down/left/right changes based on which concourse and gate she arrives in. Even for frequent travellers, only way to navigate through the terminal after each arrival is to closely follow the signs or to ask Emirates/dnata(ground handling team) employees.
Once she enters the terminal, "Connections/Transfer Desks" are clearly marked as Red. Its almost impossible to miss them.
Presuming that your mother can read basic English, navigation should not be a problem. In addition to it there are plenty of uniformed staff roaming around in the terminal and everyone will be happy to assist her.
If you are too concerned, please user Marhaba Services Transfer facility available at AED 150 per pax.