This is the last thing you need to worry about.
Learning French won't be very helpful if you later need to learn Korean, but programming languages are not like that. It's easy to switch programming languages.
The key is learning how to write code in any general-purpose useful programming language.
Python is generally considered a good language that is used in industry and also happens to be beginner-friendly, so start there.
However, learning a second human language makes it easier to learn a third (or fourth, or fifth…), the earlier the better. Completely anecdotal, but my Hungarian-Romanian colleagues all picked up German and/or English extremely quickly and completely. Growing up speaking two completely different languages must have something to do with it.
Ditto for both Ruby and Javascript. A big part of each of these being "easy to learn" is the setup time of the toolchain; for all of them (and particularly Ruby and Python) the interactive consoles are fantastic learning environments... and come pre-installed on Mac, so you have zero time trying to figure out how to get started :)
Play is the most effective way to learn (outside of classes; although I'd argue good play teaches more than classes).
Gonna show my colors here: Ruby has an advantage in "playing to learn" through SonicPi. It's hands-down the shortest distance between "learned something" and "have something to show for it", which makes it a fantastic way to play.
That said - AFAICT the driving, and differentiating factor, between success and failure in "learning to code" is having something you want to do with it. If that's ML/data processing, go with Python. If that's interactivity in a browser, that's JS. If that's a full-on website, it's Ruby.
That _also_ said - I would also strongly recommend that once she's reached comfort with one language, to pretty much immediately start learning another. Each language teaches different things, and learning what each to teach makes you a drastically better programmer overall. And, the number one blocker I've seen to seniority as a programmer is willingness to learn and work in other languages. The earlier you can "break the seal" on that, the better.
It's very much like communicating in a foreign language with only a basic phrase book. I'd like to at least be able to speak pidgin.