Make sure there are no strange devices connected to the system's USB ports or internally (there are serial and USB key loggers). Check the computer to see if there are any blue-tooth devices detected or enabled that might be used to spy on her.
Format, reinstall windows, put passwords on every account.
Also, check to make sure her wireless networks are secured, clear all of the settings on any routers\modems she's using and set them back up yourself.
As for the phone, tell her to change any account information and passwords so that her husband has no access to her account. If she isn't tied into a contract, have her drop the service all together.
If she's really serious about being spied on, try some of the (expensive!) gadgets on this site: