What could it possibly mean?

Could it mean that this woman, Ruffo’s mother, had once known Maurice, known him well enough to see in her son the resemblance to him?

But then—

Hermione, as sometimes happened, having reached truth instinctively and with a sure swiftness, turned to retreat from it. She had lost confidence in herself. She feared her own impulses. Now, abruptly, she told herself that this idea was wholly extravagant. Ruffo probably resembled some one else whom his mother and Gaspare knew. That was far more likely. That must be the truth.

But again she seemed to hear in the night the dull murmurings of those undercurrents. And many, many times she recurred mentally to that weeping woman’s question to her son—that question about Gaspare.

Gaspare—he had been strange, disturbed lately. Hermione had noticed it; so had the servants. There had been in the Casa del Mare an oppressive atmosphere created by the mentality of some of its inhabitants.

Even she, on that day when she had returned from Capri, had felt a sensation of returning to meet some grievous tale.

She remembered Artois now, recalling his letter which she had found that day.

Gaspare and Artois—did they both suspect, or both know, something which they had been concealing from her?

Suddenly she began to feel frightened. Yet she did not form in her mind any definite conception of what such a mutual secret might be. She simply began to feel frightened, almost like a child.