Replace floors, kitchen cabinets, toilet and vanity.

Simple renovations: LVT floors, paint, new toilets and vanities, new lighting.

Here in So Cal, they sell lighting fixtures and light bulbs that do not meet current codes, toilets and faucets, etc.

@Mark Frattini That was more or less my backup plan if the duplex idea didn't pan out. 

That is cleaning showers, toilets, fridge, all floors, baseboards, ceiling fans, vents, kitchen cabinets.

It does depend on some other factors (size of water heater, include expansion tank, replace the connections (new flex pipes), replace the shutoff valves (gas and incoming), gas or electric heater, installation of drain pan and if plumbed, etc.). 

If main tenant and potential main draw for traffic could go out it could send the NOI of the center into the toilet and cause a default on the loan.

Over the 5 years of living there I did a few updates including: painting all of the walls a more modern gray (previously had 3 different colors), replaced a black toilet and floor in the half bath, and revamped the backyard to remove landscaping rocks and add grass.I also had roommates most of the time I lived there so that was nice to have someone help split the bills - I gave them below market rent so it was a win-win.

The second photo should never be one of a toilet, and the first should be the prettiest you've got.  

This is the simplest method, but it also means your tenants are more likely to abuse the utilities by leaving windows open with the heat or A/C running, leaving lights on, ignoring the toilet that constantly flushes on its own, etc.3.