I'm at my mothers house, trying to help her out. She tells my that her dryer has been squeaking since she bought her home, 3 years ago. Also says that there is no noticeable difference in the squeak if the dryer is empty, partially loaded or fully loaded

There is a large belt in the dryer that goes all the way around the drum. There is a pulley that holds it tight. I would check those to see if the pulley is needing lubrication or the belt is sorry.