How do I make this old house smell better?

there actually is such a thing as scented paint. I would think a good double coat of paint through out the house ( scented or unscented) will rid you of a lot of your troubles. walls can actually smell ( or what ever is behind them). paint will help to build a barrier between you an old wood. consider putting deodorizers in your attic area. I would over do it up there. Then clean any hard floor surface really well. if none of this helps, it is probably your carpet. cleaned or not , it could be the padding underneath and may need to go.