Varies greatly due to company focus and product(s) and/or services contemplated, but diligence focus at this level is usually focused on product viability and market opportunity, competitive landscape, team and path to market.

As others have stated, this is in my experience, a unique and absurd request that is totally uncalled for and has no precedent.

Ask for a list of entrepreneur teams and companies they have funded, and google the funding rounds to look for their participation. Usually, legitimate money will be more circumspect than the less professional, and occasionally questionable sources.