New, young owners come to live at an estate in the English countryside. Servants have stayed with the property after the previous owners left. The estate house is large w/o electricity. The husband of the new owners leaves on business and the wife starts to discovers unusual events occurring in the house. She learns that the previous owners all died mysteriously over a short time. She discovers photos of them posed after their deaths. They are buried on the estate, but the gardeners conceals the headstones with leafs. I don't know how it ends.

Are you sure this is from the Thirties? I ask because it sounds like "The Others" (2001).

https://en.wikipedia.org/wiki/The_Others_(2001_film)

Here are a few excerpts:
1) Grace Stewart lives with her two young children, Anne and Nicholas, in a remote country house (https://en.wikipedia.org/wiki/Country_house) in the Channel Islands (https://en.wikipedia.org/wiki/Channel_Islands).
2) Grace finds a 19th-century "book of the dead", an album of mourning portrait (https://en.wikipedia.org/wiki/Mourning_portrait) photos of deceased family members, with some missing pages.
3) Tuttle covers the gravestones with autumn leaves, under the orders of Mills, who comments that Grace thinks the house is haunted.

Hello,
The Others seems to be the film that I inquired about. I should explain that I was a patient in a hospital when I saw it on a Sunday afternoon in 2004. I didn't see the beginning or end, and didn't see the middle entirely, either. Nevertheless, I thought it was intriguing and wished for years that I knew its title, which I missed.

The scene in the room where pieces of furniture are covered with sheets is identical to what I saw. Other scenes on the internet are very similar to what I saw, too. But, the film I saw was definitely older that 2001, and was definitely black and white. The starring role was not Nicole Kidman; it was a brunette instead.

I thought that I may have seen an earlier version of The Others, but I can't find any evidence of that being true. But, since it was a Sunday afternoon in 2004, I doubt it was a 2001 release.

Do you have any thoughts?

Sincerely,
Ed