Wow, 3mo is a long time for that long NW... (((hugs)))! It happens every night?!
We have played with bed time and a later bed time only results in an even earlier, painful wake up call from her.
Have you tried an earlier BT... 7 or even 6:30? Because you mentioned a later bedtime makes for an earlier wake and she's been waking for so long, I'm wondering if those NWs are possibly be due to OT (overtiredness) and an earlier BT might help.
The other thing that might be worth a try is to push the morning nap later to 10:30. It's quite normal for a 10mo old to be on 4hr A time. That may make the first nap extend to 1.5hr, which means you could cut the afternoon nap to 30min and she may in turn have more drive to sleep at night. This would be looking at the NW as more of a UT (undertired) issue.
What do you think? Are either of those things doable?
The other factors to take into consideration with long NWs are discomfort issues like teething, reflux, food allergies/intolerances (although with all of those things I don't know that she'd be waking happily
). Environmental factors can come into play as well... is it cold in her room come 3-4am? I can't imagine there would be any noises happening consistently at that hour, but it never hurts to rule everything out.