Hi i'm going to visit my grandmother who lives in Mirabella Eclano, a very small town outside Naples, also near Avellino. I know there is a bus that takes you directly to the town from Rome but I am having a terrible time finding it. Any advice????

Here is a website about Bus in Italy -
http://www.bus.it/principale.htm
However did you check on train connections / On the countrary than the Americans, Italians tend to use trains much more frequently. Trains are also inexpensive - fast and well connected.

do you have a link to train routes as well?
grazie

Here is the train schedule
http://www.trenitalia.com/en/index.html