Lawn / grass help

Last year my mom had two giant water oaks removed. Beforehand she had St Aug between and around the trees. The guy who came in put grass on top of the ground stump… no filler sand/dirt. Now there are two large dead patches filled with weeds, and what was St Aug between them is now something else. A landscaper said it looks like centipede.

I’ve posted before how I've tried to kill what looks like wild carrot (Winter weed cocktail followed by Trimec weeks later), but it keeps coming back.

What’s the best course of action? Nuke it and start over?

Here are some close ups of what is in the yard today