I see you posted a similar question previously, and it seems that most forum members have a different idea about what constitutes an age-appropriate garment for a women of this age than you do. I'm not sure if there is a cultural norm we're ignorant of, but I personally have no knowledge past what you've stated in your post, and what a cursory Google search turned up.
With the above in mind, I looked at the images in your link, and I notice all of them feature a cropped top. When I did a Google search, I noticed there are also a lot of options with a full top available; I would go that route. However, if you have your heart set on this type of midriff revealing top, I'd suggest choosing an ensemble that meets the following criteria:
- a scarf that is long enough and not stiffly beaded, so it can be worn wrapped around the body if she would like more coverage
- a top with 2 wide straps or with sleeves, rather than an asymmetrical one-shoulder top, so she can wear a properly supportive bra underneath
- a top that extends down the rib cage and resembles an actual cropped bodice, rather than a very skimpy top that resembles a bra
Of the images you linked, I would choose #2, which has long sleeves, and extends the farthest down the stomach.