I've had calls where I could have just reset a breaker and left. After doing a safety evaluation of their electrical system and presenting them with my findings I've ended up installing GFCI receptacles, whole house surge protection for power, phone, Satellite and other items in the home. Mention installing a dimmer switch when changing out the light bulb. You can give them a discount since you're already there.
I carry a z-wave dimmer & lighting demonstration kit with me and demonstrate how they can control every light in the home from their bedroom, car remote, etc. Set up timed events to give the appearance that they are home while the're away. I also mention door bell intercoms with cameras so they can see who's at the door and reply without opening the door. The elderly really appreciate this kind of stuff and have no clue this stuff is available.