Well, as you saw, the Clip automatically creates empty folders for the user, seemingly to make file organization easy. But I’m not sure that this would make any difference for you.
First, you don’t have to use those folders. And so simply place the files you want your mother to play at the top-most level of the memory card–that is, at the same level as the folders that the player created (but not inside those folders). Hopefully, then, your mother’s player will be able to recognize and play them and simply will ignore the empty folders on the card. From the description of your mother’s player at the Amazon site, I think this could work.
In fact, as Tapeworm notes above, you even may be able to place the files in the folders created by the Clip, if you wanted, and your mother’s player may be able to detect and play the files just fine. But you and your mother would need to check this out with her player. Absent that, the simplest and “safer bet” would be to store the files on the top-most level of the card, as noted above.
Second, if those empty, created folders cause an issue for your mother’s player, or if you just don’t want them there as possibly causing confusion, you may be able to get rid of them easily: once you have connected your Clip to your computer and transferred your files to the external card at the top-most level, delete those extra, unwarranted folders from the card using your computer, use your computer to “Safely Remove” the Clip from the computer (that is, electronically disconnect the 2) using the computer’s “Safely Remove” feature/icon (in the computer’s Notification area), and then remove the card from the Clip–this could eliminate the folders and remove the card from the Clip before the Clip would recreate the folders.
I don’t have a spare memory card to put in my Clip right now to test this second option out for you. But if you would like to test this, as Tapeworm notes above, you can pick up a card reader inexpensively at Amazon.com to do so. (For that matter, you could skip the Clip entirely and simply use the card reader to put files on the memory card.) Alternatively, if the Clip recreates the empty folders before you have a chance to remove the memory card, you also could try simply removing the card from the Clip once you have transferred the files to the card and deleted the emplty folders and before the Clip might recreate the folders, without using the “Safely Remove” feature, if you are absolutely sure that no communication is taking place bewteen the card and your computer–however, if you are wrong about that, you could damage the card and make it unusable (and why I would avoid using this alternative). The reason why always to try to use the “Safely Remove” feature on your computer, to disconnect.
My guess is, the first of the above options–putting the files at the memory card’s top-most level–should work for you and your mother’s player; howeer, only using the memory card with your mother’s player will tell (these small card reader players can be very idiosyncratic in what they will do and allow).
Hope this helps–try it!