Perhaps she even anticipated a violent death.

And then Mrs.Octagon hinted that she knew who had killed her sister.

It might not have been Caranby after all, whom she meant, but one of the Saul family, as Mrs.Mallow suggested.
"I wonder if it is as my mother thinks," mused Cuthbert, staring out of the window at the panorama of the landscape moving swiftly past.
"Perhaps Selina did kill Miss Saul, and shut herself up to avoid being murdered by one of the relatives.

Caranby said that Selina did not go to the inquest, but pretended she was ill.

Then she and her sister went to the continent for two years, and finally, when they returned, Selina instead of taking her proper place in society as Isabella did, shut herself up as a recluse in Rose Cottage.