This is a 10' wide L-shaped area between deck and house.
Saw some Dwarf Mondo on a garden tour last week and the gent who was
growing it says it really forms a mat. It looked like it to me.

If it is like the dwarf mondo grass that my neighbor has, it should.
Slow growing, though, so it might take a while to form said mat.

My garden book recommends mondo grass when growing on a smaller scale
than where you'd plant Liriope. So I don't know if the mondo grass
would look good in a 10 foot wide space.

There are also quite a few native plants which are somewhat similar
but of course that will depend on where you are (here in Washington,
DC I think of some of the smaller sedges and grasses, and "blue-eyed
grass" which is in the iris family, no doubt others).