The exterior would have all the classic elements of a Victorian building (lots of decorative features but a uniform, dark color) and the interior would also be styled like the time with over-the-top decor. If you Google Victorian interior design, you'll see a lot of the same. Throw pillows, figurines, china cabinets, large paintings, etc. Essentially a housemaid's worst nightmare. I'll include a few specific images I found that would be similar to the way the Hygrace manor looks specifically ^^

[hider=Victorian interior][img]https://i.pinimg.com/originals/a7/87/1f/a7871f9fdadab8a1ff9367135df0f6c2.png[/img]
[img]https://hips.hearstapps.com/hmg-prod.s3.amazonaws.com/images/tcx100117sisley006-1505845092.jpg[/img]
[img]https://i.pinimg.com/originals/67/95/76/679576d05a8dcb2b1024f8463b6bef07.jpg[/img][/hider]

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EDIT: I forgot to mention the one feature that would be missing is mirrors. Since it's a family of vampires with no reflection, they have no use for them.