The Stone doesn't bring back the dead, and "Master Of Death" is just a title, not literal.
Firstly, the Resurrection Stone doesn't bring back the dead. Rowling has gone on record as stating that magic cannot bring people back from the dead.
...one of the most important things I - I decided was that magic
cannot bring dead people back to life; that' - that's one of the most
profound things, the - the natural law of - of - of death applies to
wizards as it applies to Muggles and there is no returning once you're
properly dead, you know, they might be able to save very
close-to-death people better than we can, by magic - that they - that
they have certain knowledge we don't, but once you're dead, you're
dead. So - erm - yeah, I'm afraid there will be no coming back fro-
for Harry's parents
The Stone conjures apparitions that very much appear to be the "ghosts" of the dead however, so what gives? Look at how they are described.
They were neither ghost nor truly flesh, he could see that. They
resembled most closely the Riddle that had escaped from the diary so
long ago, and he had been memory made nearly solid. less substantial
than living bodies, but much more than ghosts, they moved toward him,
and on each face, there was the same loving smile.
Well, we know of at least one other instance that produces similar shadows - Priori Incantatum.
...though the thick gray ghost of Cedric Diggory (was it a ghost? It
looked so solid) emerged in its entirety from the end of Voldemort's
Dumbledore later explains this effect.
"No spell can reawaken the dead," said Dumbledore heavily,
would have happened is a kind of reverse echo. A shadow of the living
Cedric would have emerged from the wand... am I correct, Harry?"
spoke to me," Harry said. He was suddenly shaking again. "The... the
ghost of Cedric, or whatever he was, spoke."
"An echo," said
Dumbledore, "which retained Cedric's appearance and character..."
It seems likely that one of the Perverall brothers succeeded in recreating the effect of Priori Incantatum, and bound it to the stone.
Master Of Death
Basically nothing about the afterlife side of the legend of the Hallows is true - it's all stories and metaphors that sprung up around several powerful wizarding artifacts created by three brothers. Dumbledore states this, and as we know, his guesses are usually right.
“—were the three brothers of the tale,” said Dumbledore, nodding. “Oh
yes, I think so. Whether they met Death on a lonely road . . . I think
it more likely that the Peverell brothers were simply gifted,
dangerous wizards who succeeded in creating those powerful objects.
The story of them being Death’s own Hallows seems to me the sort of
legend that might have sprung up around such creations
The title "Master Of Death" simply means that the user has the ability to kill (the wand), to hide from death* (the cloak) and to not forget the dead (the stone). All sides of death are mastered, hence "Master of Death".
*Note, this means hide from danger, not hide from Death, the non-existent character from the story.