You have described a very wide gamut of photography, and, unfortunately, when you leave the world of the fixed-lens superzoom camera behind, covering all of those bases begins to get very expensive. The best you can hope for within your budget is to avoid disappointment as much as possible -- you can buy an awful lot of low-cost gear that looks like it will cover the territory, but will generate disappointing results. You can, however, put together a system that she will not immediately outgrow, and which she can build upon gradually as needed.

The biggest hurdle to overcome is the lens selection. DSLR camera bodies may turn up at bargain prices after they've been superceded, and you can find them cheap on the used market, but good lenses tend to start out relatively expensive and stay that way. The sort of lenses used for most wildlife and sports photography tend to induce irrational lust in the photographer and financial panic in their loved ones. That is, they're pretty and godawful expensive. You might want to leave the long fast lenses for another day (or year). There are lenses that try to do everything (18-200mm, 18-270mm, etc.), but they tend to be expensive, and their performance shows the folly of the attempt. With the various genres you want to be able to cover, something that starts wide and finishes at a more moderate length, and does well over the whole range, would be far more appropriate. Wide-ranging zooms have one serious drawback for the serious photographer, though: they have a limited maximum aperture, so it is very difficult to create pictures where the subject is in sharp focus and the foreground and background are blurred into a pleasing pattern of colour with no detail. It would be good, then, to have a lens in the kit that is not nearly as versatile, but can do that one job very well.

On the other hand, your timing is good. We tend to discourage this sort of question here because the answers are not perpetual -- they apply only at a given moment in time. Right now in the Canon lineup, there is a new entry-level body, the EOS T4i (650D outside of North America), which is a remarkable improvement over past models when paired with Canon's new series of lenses with stepper-type focusing motors (STM). It's not so much that the image quality is better, but that the autofocus system is less prone to error.

At the same time, there is a new EF-S 18-135mm f/3.5-56 STM lens which by all accounts is a vast improvement over Canon's previous attempts at a wide-range zoom. And it allows for much better operation in video mode (real-time autofocus is possible with bodies that provide the feature). Together with the T4i/650D, they'd form the basis of a kit that would cover a lot of territory and wouldn't immediately need replacing.

If you throw in an EF 50mm f/1.8 lens (it's cheap but competent), you also provide her with the ability to selectively focus and to work in low-light conditions. And you'd still have room in the budget for a bag, a few memory cards, perhaps an extra battery, and a tripod that's worth having (depending on the prices you're able to find and any sales tax liability, of course).

One ought to be able to build a similar system around the Nikon D3200, D5100 or the Pentax K-30 as well. Don't be afraid to look outside of the Canon lineup. The principles will be the same: a body, a zoom lens that starts wide and has a moderately long top end (and read the lens reviews you can find on Google to find out if they're at all good), and a single fast-ish f/1.8 lens at 50mm (usually very cheap) or 35mm (a little more expensive). You can also put together a similar system in a mirrorless camera (APS-C or Micro Four Thirds), though if she's an experienced photographer, she may be uncomfortable without a "proper" viewfinder. In any case, you will be looking at a starting point rather than a turn-key compleat photographer's studio in a bag.