The answer is the same for each plant in your two threads: Pull them out of their pots and examine the roots. If they're all dried up, the plants are goners. If they're still alive looking, go ahead and plant them...but do it soon. The Muhly looks like it has a better chance than the Pampas, but the roots will tell the story.

Oh, and to clarify, I am in Collin County (Plano) Zone 8a - clay soil. Where I want to plant pink muhly grass is in the 4'x25' hell strip between my back 18" retaining wall+6' fence and alley. It's currently St. Augustine and I have a sprinkler system with what I think is an excessive number of sprinkler heads in this section seem to mostly water the alley. I figure I could either cap those (no irrigation) or convert them to drip/soaker hoses, but they share a zone with sprinkler heads in the backyard that water a St. Augustine area I'm keeping as turf so they probably wouldn't run long enough to properly soak. I moved into my current house in late August 2019 and I'm trying to find as many areas/ways to cut down on water use in my landscape wherever possible, as I now have to water enough to keep my slab foundation, four large red oaks, one large live oak, one huge pecan tree and St. Augustine happy. The amount of water this takes was honestly staggering compared to my water use at my last place when I had a hose end drip system garden and a bermuda lawn I would just let go dormant in late summer. That was probably more info than you all needed, but I felt like sharing.

It's a fall blooming grass. In lower SC, it would be glorious around Thanksgiving.

i think this is what i just saw down 5 miles of roadside shoulder here in my MI ... based on sunlight.. i though it was purple ... but i didnt slow down to say it couldnt have been pink ... i rather enjoyed it .. just goes to show.. an evill garden pest.. can bring enjoyment .. as long as its not in your yard .... ken