But she didn't have to be there. She wasn't Jesus' next of kin; there would have been no pressure or social expectation demanding her presence. She could have stayed away, could have spared herself the trauma and anguish, and the likely abuse from onlookers. Nobody would have blamed her. But no, she was there, right to the end.
We do not know what purpose her presence served. Did Jesus see her, and draw some comfort from this? We don't know. Was she able to support Mary and other relatives? We don't know. All we know is that she was there, and I believe this was because she couldn't have been anywhere else. Her love was too great, too strong, to keep her away. Even if being there was dangerous and agonising, even if it was a useless, futile gesture and Jesus never knew she was there, still she stayed, still she had to be there. That alone should make her the patron saint of constancy, and a sure companion for all those who stand at the foot of so many crosses, accompanying loved ones in their suffering.