In Chapt. 16, as Anne is contemplating the (unpleasant) possibility of an alliance between her father and Mrs Clay:

"The evil of the marriage would be much diminished, if Elizabeth were also to marry. As for herself, she might always command a home with Lady Russell."

In other words, she would refuse to live under the same roof with them, and assumes -- because it's true, I think we can agree that we seeing a combination of Anne's particular PoV with that of the ON -- that Lady R will be glad to take her in as a daughter on a more or less permanent basis.

Note how, almost like in cinema, Anne's thinking of Lady R shifts the scene to what Lady R is actually doing, in the very next line of the text:

"Lady Russell's composed mind and polite manners were put to some trial on this point, in her intercourse in Camden Place. The sight of Mrs. Clay in such favour, and of Anne so overlooked, was a perpetual provocation to her there; and vexed her as much when she was away, as a person in Bath who drinks the water, gets all the new publications, and has a very large acquaintance, has time to be vexed."