A French Press requires hot water, so that isn't really an option, unless you just use the container for steeping/filtering.
Cold brew has a milder flavor because hot water makes the beans release acids, which make the coffee more bitter.
The secret of cold brew is that it's dead easy. If she likes the taste, why not buy Starbucks coffee at Costco? Buy the whole beans and grind them on the coarsest setting.
The absolute easiest way to make cold brew is to get a large glass jar, add desired amount of coffee, fill with cold water, close, and shake vigorously. Shake again every couple of hours. When it's as dark as you like (or more - you can always dilute with fresh water), let the grounds settle and pour off as much as you wish. Heat the coffee and that's it. Refrigerating the brew while it's steeping is optional.
I found a canning jar that has a filter, which simplifies things a bit, but it's kind of messy, so not really an improvement over the method above. At least I got it at a thrift store.
When I make coffee for a crowd, I use a two gallon cooler and paint sieves, which are cheap and washable. I start it the day before. Before serving, I dilute with water and run it through the coffee urn to heat and serve. Easy-peasy and everyone raves about my coffee, which I find hilarious, because I don't drink the stuff myself.
Oh, and cold brew reheats better due to the lower acid levels, I'm told.