The melting point of Hydrogen at atmospheric pressure is 14.01 K, for comparision the current temperature on Eris is around 18 K, so in outer KB the temperature is low enough to freeze it.

Helium cannot freeze solid at atmospheric pressure or in vacuum at all, but I wonder; could it be the component of some KBOs interiors where it is frozen by high pressure along with lower temperature?

Noble gases freezing points (at 1 atm. unless specified otherwise);

Helium (at 2.5 MPa): 0.95 K
Neon: 24.56 K
Argon: 83.80 K
Krypton: 115.79 K
Xenon: 161.4 K
Radon: 202 K

Also, another question, can be frozen chunks of these gases floating in the interstellar space near or in nebulas where solar system is being born?