My fiance and I were discussing this, I think the message Minfilia got was telling her to let us go, and for her to save her allies. The only possible reason to run back in there would be to save Y'shtola and Thancred from the rubble, they collapsed the tunnel, there would be no guards coming through after them, if those two were dead, there would be zero reason to go back. I also find it quite interesting that the only two people to confirm the sultana's death is Adeledji and Ilberd, neither are trustworthy to their word, and Adaledji didn't even touch the body, he simply looked at her and gave a "yeah bro, she ded" the only trustworthy character that refers to the sultana says that she's violently ill. It's kind of interesting imo