Between Elements and Ligthroom, I'd go with Lightroom. It will still be useable once/if she adds Photoshop (which would make Elements redundant), and you're also getting a fast workflow tool (organizing/editing/printing/uploading).

I haven't spent any time with Aperture, but the tight integration between Lightroom and PS would keep me with Adobe. It's great to be able to launch an image you've edited in LR as a SmartObject in PS, as well as having some other handy commands like merge to HDR from Lightroom.

Only downside of LR, is it's terribly slow with really large files (ie scanned 4x5s). It doesn't use a scratch drive like PS, instead it eats RAM/processor. However for RAW DSLR files it's fine.