Doesn't matter what the DM rolls, beholders eye petrification is a DC only ability, it always hits, its up to the player's DEX Save to resist the effect.
Petrification Ray. The targeted creature must make a DC 16 Dexterity saving throw. On a failed save, the creature begins to turn to stone and is restrained. It must repeat the saving throw at the end of its next turn. On a success, the effect ends. On a failure, the creature is petrified until freed by the greater restoration spell or other magic.
And they failed because they didn't have the paladin by their side
Doesn't matter what the DM rolls, beholders eye petrification is a DC only ability, it always hits, its up to the player's DEX Save to resist the effect.
https://5e.tools/bestiary/beholder-mm.html
The DM rolled a 3: Fear Ray
Then the DM rolled an 8: Petrification Ray
And the person failed their saving throws, resulting in the above conditions.
Doh, I completely overlooked that, thanks for pointing it out.