Radak #1: I know that you are Ish Elokim because you revived my son. I know that Hashem's word in your mouth is true, for you said that the jug of flour and flask of oil will not lack, and so it was.

Radak #2: When he asked her to give to him her son, he said, in order to revive him. Like he said, so it was. She said that she knows only now, for merit of the Navi could bring Brachah to the flour and oil - "Yetzav Hashem Itcha ¹ Es ha'Brachah ba'Asamecha" (Devarim 28:8). However, we do not find [promises in the Torah for] Techiyas ha'Mesim [before the end of days].

Malbim: Before, a Safek was aroused in her mind whether the Brachah of flour and oil was Hashem's word, or due to Eliyahu's power, or witchcraft.