That particular bit of dialogue is very much open to interpretation, so I don't think it's possible to offer an empirically grounded answer here.
My take: in order to decide what Epione meant by "It's right", we first need to decide what she meant by "Honor us" and "Seal it", to put what was said in-between those two statements in it's proper context.
Firstly, what did Epione mean by "Seal it"...? As noted in Scanlan's answer, this is likely a callback to one of the other Amazons stating about a minute earlier that they "must seal the cage", presumably in an attempt to trap Steppenwolf within the chamber. This is indeed what is done as Hippolyta leaves the chamber with the Mother Box.
So what did Epione mean by "Honor us."...? Well, she was seriously injured and quite possibly dying when she made that statement, and I think she'd determined that the Amazons within that chamber were fighting a losing battle, and that those who weren't already dead soon would be (unless they fled, which most of them had no intention of doing). As such, the fate of most of those Amazons was essentially sealed, and Hippolyta could either stay and die alongside them, or leave and try to survive long enough to honor their memory. Epione seemingly wished her to take the latter option.
So when Epione said "Honor us. It's right. Seal it.", I think this was a truncated way of saying "Honor our memory. It's the right thing to do. Seal the chamber."