For those in the US, or with US citizenship, the Library of Congress has a National Library Service for the Blind called BARD (Braille and Audio Reading Download), which works either with a dedicated hardware player (functionally designed but with excellent usability) or Android / iOS apps. Both players and books are free.
NLS: <https://www.loc.gov/nls/>
BARD: <https://www.loc.gov/nls/braille-audio-reading-materials/bard...>
Player: <https://www.loc.gov/nls/enrollment-equipment/equipment-neede...>
The titles selection, as one might expect for the Library of Congress, is excellent. No, it's not everything in the Library, but it exceeds any other audiobook service I've found.
There's a pretty good catalogue interface. You can either order books on cartridges, or download them to a USB stick which is inserted in a port on the hardware player. For the apps, materials are downloaded directly to the device and selected for play via the interface.
For the completely blind, I'd recommend the hardware device as it's far easier to navigate than touchscreen smartphone / tablet interfaces.
Materials include not only books but many magazine publications.
Eligibility requires a statement from one of numerous specified medical professionals or caregivers, and is straightforward.
I believe OP is based out of France, which has its own books for the blind programme: <http://www.bnfa.fr/>
<https://www.theguardian.com/society/2013/dec/31/digital-audi...>
Public and academic (e.g., community college) libraries also typically have access to audiobooks through various programmes, usually commercial services (Libby and Axis360), as well as CDs. Selections through these services are typically much more restricted than BARD.
Librivox has a large selection of public-domain and liberally-licenced (e.g., Creative Commons) works. Quality varies widely but is usually listenable and is occasionally quite good. (A friend from another online community mentioned a book he'd narrated and I was stunned to find it was absolutely professional-grade work. He has an excellent radio voice, and did some professional voice-over work.)
I would strongly recommend experimenting with, using, and deciding on specific accessibility tools whilst she still has some sight. There are assistance tools for MS Windows and MacOS, as well as some options on Linux systems, and of course mobile devices. Find out what works for her now, and find out what the capabilities and limitations of these tools are.
I'd also strongly suggest switching up from a smartphone to a tablet which might be both easier to read and offer better reading options as vision degrades. I'm strongly partial to e-ink devices, though these tend to have reduced contrast. This is less an issue with "frontlight" (or auxiliary external lighting), but something to consider.
Devices with hardware controls may also be preferred to touch. Consider items such as phones, large-character keyboards, and the like.