Yes, Moiraine can do that. Again, WoT channelers don't have to aim all that much, they just have to see (or, in a number of cases, just know where their foes are). Again, if Sypha started 10 feet away, her comic book agility and speed might let her keep away from Moiraine's attacks. If she had tons of cover to use, maybe, but even then, Moiraine knows Balefire. Here, she has neither, and Aes Sedai, not even powerful ones, grab multiple warders (who are all well beyond real-world humans in speed and such) and string them up like ragdolls instantly, before they can do anything, several times in the series. Moiraine is stronger than those people, and certainly has an angreal which multiplies power and responsiveness. Moiraine also knows compulsion (mind control), can send out waves of fire herself, can cast illusions, etc. Sypha's fire attack is just begging to be used against her - manipulating fire is trivial for Aes Sedai, as it's not even a complicated weave, it's just one of the five flows. The situation here just strongly favors Moiraine, because the two people face each other at a range of 100 feet and there's no cover. One of the people's attacks have to form and cross distance. One of the people's attacks doesn't. Even balefire, an attack that neither Trevor nor Sypha has the slightest answer for, forms instantly in a line from the target back to the caster. I'd favor the one who doesn't need her attacks to cross the space.
Aes Sedai get taken by surprise sometimes, sure, but often it's PIS. They react stupidly quickly very, very often.