It's not stated in the book or any other media that I know of.
She of course would not keep using Bellatrix's (she is disgusted by it and she is not the master of that wand).
The obvious answer is, in my opinion, that the Ministry raided Malfoy Manor after the war, and recovered the stolen wands.
And what if the wands were destroyed? I don't think the Death Eaters would destroy useful wands, but she was considered a mudblood so that's a possibility. In that case, Hermione would have simply bought a new wand at Ollivanders.
Luna also lost her original wand and got a new one from Ollivander. Hermione says in Deathly Hallows that she wishes he made another one for her.
“I miss my wand,” Hermione said miserably. “I wish Mr. Ollivander could have made me another one too.”
Mr. Ollivander had sent Luna a new wand that morning. She was out on the back lawn at that moment, testing its capabilities in the late afternoon sun. Dean, who had lost his wand to the Snatchers, was watching rather gloomily.
Harry Potter and the Deathly Hallows, Chapter 26, "Gringotts"
We also don't know if Luna recovered the original or kept using the second.