1:56 last 800 in a 1500 is insane for a woman. But remember she is a 3:50 runner, she's 6 full seconds faster than the next fastest woman competing in this race.
It's not unbelievable at all to think a 3:50 runner could close that fast after going out in 2:25. Hell 2:25 per 800 is probably almost her 10k pace at this point!! Either way that was an incredible race, I'd love to see her take a run at the 800 record, I betting she can go 1:54 low right now.