This mods subfolder and the PHP file and image file within it are shared by numerous mods,
specifically, mods I wrote and that have mod options.
They folder and files are shared in that they are packaged with (zipped up with) each mod,
and that the two files are installed by any one of those mods -
the one that happens to be installed first on a TNG site.
This folder should not be deleted unless you have unistalled and deleted all of the mods that use it.
To figure out whether you have done that, just do a global search of all of your .cfg files,
looking for the name of this subfolder,
which is in the form shared_mod_settings_blocks_v#.#.#.#.
See the Mod Settings Blocks Wiki article
for details