It's possible if she doesn't know why you're asking the questions and requesting a specific photograph, her responses won't be helpful.

For example, if you asked for a selfie, she might just think you want a picture of her, and she remembers that she has a picture of her that she took last year where she looked good (passport phot that people dress up for), and wants you to have a good photo rather than one where she looks miserable in a hospital.

The way you tell the story makes it sound suspicious, but next time I would just be direct and tell her something seems suspicious to you, that someone could impersonating her, so that is why you are asking.

If someone is targeting you, chances are they already saw your comment here so that hypothetical person already know you're on to them, so saying that on the phone won't give any new information away.