I need some help with a Card/Unit

You mean Nod Cyborgs (The Crawlers/Railgun)? They're infantry and are extremely strong right now because everything that is effective against them, they are also effective against. Your best option is using regular Infantry to go toe to toe with them (Flame troopers melt anything that is Infantry). Nod's Flame tank should melt them as well and be able to survive their damage as long as it doesn't get surrounded by them.

Sandstorm (Hover Tank/Shoots Missiles)? They're very fragile but dish out tons of damage extremely quick (To multiple tiles), however a bulky unit such as the GDI "Titan" or Nod "Rockworm" will absolutely smash it to pieces. Nod Cyborgs will also melt them.

Rockworms are a struggle to deal with for GDI unless you have the Orca, Nod's Banshee's can just follow and harass it as it surfaces. If you can't deal with it, just have your harvesters avoid it and have flying units to contest the missile if they use it to hold a spot. It has to be unborrowed for it to count as occupying the missile so a single flying unit can make it pretty useless outside of it chasing your harvesters/troops around. You won't see many of them but they're just too much of a hassle to kill, it's better to just play around it because it's way too damn tanky and escapes too easily.