Answer:
Her bravery and strength is unwavering.
Step-by-step explanation:
The sentence shows that the mother of the speaker had a courage as strong as a rock, that is, unshakable, difficult to be provoked or diminished and resistant. In other words, the speaker shows that the mother's bravery and strength were already unshakable, as she was able to continue even with the world's biggest problem on her back, promoting the protection and defense of their children and herself at all costs .