ARD 3 and ARD 2.x and an 87 year old mother!

Here is the deal. My 87 year old mother has an eMac and a DSL connection, no router. Before we moved her to a new city and different DSL provider, I could control her Mac with my G5 and ARD 2.2. Now, I have a new G5 and a MacBook Pro with ARD 3.0 and mom still has her eMac. I can see her name, and get the ip address, but that is it. We have all the settings on both machines on (but would like to have a checklist to be sure we are accurate), and the ARD timesout and won't connect. I know this has to be something very simple, but I have no idea and my mom isn't getting any younger! We are about to buy two more Macs, one for each of her sisters (ages 70 and 90) so they can all iChat. But guess who gets to watchover all three?
We are all at the end of our ropes with this problem as I have tried since spring to get this fixed. Certainly appreciate any step-by-step advice.
Thanks in advance for your help.

Phil