We have all been there, so frustrated that they were doing amazingly well at their sleeping last week and now **BAM** they aren't.
Here are two things I'd try. First, can you make that last nap a little earlier? There's only a short break between the 4.30 nap and the 7pm bed time. If you could bring that last nap forward, it might help because she'll be less rested before bed. The other thing I'd try is to shorten the last nap a bit, if there's too much sleeping before the bedtime, she might just not be tired and that's why she's waking during the night.
See how those ideas go. Good luck!