Buying property through a company IHT considerations

[Esotericstuff]

My elderly mum has a lump of cash in the bank doing nothing, but no pension to speak of. Previously she survived (very modestly) off the rental income from renting rooms in her home to lodgers, but for health reasons can't manage anymore. I am looking for some advice on how to help her invest and on how to make it IHT efficient.

Looking to the future (which sadly might not be that far ahead), would buying a BTL property/properties through a business where we are both directors be a way to reduce the IHT owed on her estate?

I estimate a 4.5% yield on her investments would be adequate to maintain her lifestyle comfortably.