So, is this what her day looks like?
Wake 9:30am
Nap 1 11:30-1:30pm
Nap 2 4-5pm
BT 9ish (cries for 20min, asleep at 9:20/9:30pm?)
At 16mo old, most LOs are making the transition to one nap. My guess is that she's not really ready for bed at 8:30/9pm as she's had a lot of day time sleep over 2 naps, so she fights it. Have a read through this link:
From 2 to 1 nap transition (10-12m and older)Is she getting any teeth right now? Does she show signs of separation anxiety at other times during the day? It's normal for a LO to prefer one parent over the other at bedtime. When she cries at BT, are you in the room with her?
I'm going to move this over to Sleeping For Toddlers, as your LO is over 1yr old.