If that was the UK 1881, that column is headed "relationship to head of house" and the reply is "husband". Also, the Aiken children are all listed as "son"or "daughter". To me that suggests that Margaret is either Mrs Horatio or Mrs "somebody not home" and Horatio would surely then describe himself as "brother in law" or some other relationship. That's why I assumed that it was mMargaret's house.
Of course, I'm not an expert on USA genealogy.

I think that you need to know (1) when Leonard died, (2) is there a re-marriage for Margaret under either her maiden or married name, (3) is there a death for Horatio.

If Margaret's reverted to her original married name in 1886, there's possibilities, and you can probably think of more: Horatio died and she was more comfortable with the same name as her kids; she and Horatio were not legally married and he's left; he turned out to be a bigamist and got caught; divorce, etc... I would have thought that if it was anything even faintly scandalous, since he was a lawyer, it might have been picked up by local papers.