How about a nice big NEW front door mat?
Don't personalize it... I don't think it is a great idea to have your name emblazoned outside of your house like that, personally... And nothing crazy in style, unless you REALLY know her WELL. Just plain and simple, something with gray scrolls that looks nice. Maybe says 'Welcome' in the middle or something...
Or a nice big potted plant (if she doesn't already have a gazillion of them). I love them, but half die quickly and a few manage to survive for more than one year or so. But I LOVE having them around and it can be a pain to have to shop for and put one together.
Wine and cheese. If you wanted to make THAT personal, get the glasses at a Things Remembered type place that can engrave their new address or the date of closing or moving date on them, as a nice memory down the road...
ETA: Be cautious with candles. Unless you know she likes them, skip that. I like/love the "idea" of candles, but I almost NEVER burn one. They just become dust collectors in my house. The ONLY thing I ever do burn, is at Christmas... and that is one of those wax pot pourri burners, with the melty scented disks. Those just take tea lights, don't make smoke or smoke detectors go off and burn out quickly so no worries really about leaving something burning on accident.