At the beginning of Game of Thrones season 7 Melisandre has the following exchange with Varys when Jon Snow arrives at Dragonstone...
Varys: I wondered why you weren't there to meet our guests.You begged us to summon the King in the North, don't you want to see him again?
Melesandre: I've done my part. I have brought fire and ice together.
Varys: Strange, you spoke so highly of Jon Snow, but when he arrives you hide on a cliff. I didn't take you for a bashful girl.
Melisandre: My time of whispering in the ears of kings has come to end.
Varys: Oh, I doubt that. Give us common folk one taste of power, we're like the lion who tasted man. Nothing is ever so sweet again.
Melisandre: Neither of us is common folk anymore. I did not part on good terms with The King in the North or his adviser.
Melisandre: Because of mistakes I made, terrible mistakes. I will only be a distraction if I stayed.
Varys: So, where will you go? I'm not sure you'd be safe here.
Varys: Good. If you don't mind my saying, I don't think you should return to Westoros.
Melisandre: Oh, I will return, dear Spider. One last time.
Varys: My Lady--
Melisandre: I have to die in this strange country, just like you.
As the exchange shows, Melisandre tells Varys that she is going to Volantis, possibly suggesting she is going home to her Red Temple to gain insight on how to help defeat the Night King when she returns. Many speculated that she may bring many red priests and priestesses back with to her help in the fight for the living!
But as the Long Night happens in episode 8.03, Melisandre does indeed return, but she returns alone with her efforts, although significant, not much advanced from the magic that she had used before. Actually, besides the flaming swords and fire-summoning incantations, she doesn't even resurrect anyone and pretty much serves to help trigger Arya's purpose.
So my question is, did she really go back to Volantis, because why wouldn't of she brought back more help and/or have shown greater power?