Is it true that Elena become a vampire at the end of the third seasone? And when are they going to release the season four?

Yes, it's true. Elena becomes a vampire and the release of season four: Thursday, October 11

It seems to me that she will not become vampire. But I do not have other information.

Technically she's in transition of becoming a vampire, but yes, most likely she will become a vampire and stay a vampire in season 4. And season 4 comes out in October on the 11th.

Ellen's dies in the end. and she is annoying 😂