Honorable Sheikh, may Allah protect you, if the time for prayer enters.

And the woman, may Allah honor you, goes to the bathroom to purify herself and sees menstrual blood.

She does not know whether this blood came before the adhan or after it, so what is required?

The basic principle is that it did not come before, so if she becomes pure, she should make up the prayer whose time had entered.

Except if, for example, as soon as she heard the adhan she quickly went and saw the blood, then most likely this was before the time, and if it was before the time, the prayer is not required of her.