After Diana was picked up from the road, the couple brought her to their home, where the old woman asked them where they saw the child.
Being someone of kind nature, the woman didn't mind it and accepted Diana.
The old woman was stalked by Maris, who told her everything, because it's only then can the couple agree to leave town.
The old woman knew Stella to be a good girl, same as Stella's mother. She knew there's nothing she can do for Stella, but also knew helping Diana will mean doing a lot already.
She accepted the child and already knew beforehand that someone will approach her son to leave town with Diana. Knowing this, she agreed with it, since leaving a town doesn't mean leaving the world.
It's the same human being like them that lives in those towns.
