It's possible for a farm to be snowed in. This simply means that it is surrounded by snow to the extent that it is not possible to get in or out of it. If we speak of the farmers being snowed in, it would be redundant to say that they stayed at home. It might not be redundant to say that they stayed indoors. If a farm is snowed in, it might still be possible for farmers to get to parts of the farm, unless the farmhouse itself were snowed in.