I include non-paying tenants as part of the vacancy risk included in calculations I make prior to purchasing a rental to ensure it will cash flow.

A great agent will also invest in home, pest, and roof inspections to remove doubt in a buyer's mind prior to making an offer.

@George RedCalifornia is generally more cumbersome than other states when it comes to taxes and filings.

We have 2 years of reported rental income on tax returns for both properties.

It's likely they aren't including all expenses including property management, taxes, insurance, mortgage payment, and capex/vacancy/repairs holdback. 

Would my mother's portion be affected or are their tax implications for her with this type of transaction?

For instance, let's say I remodel the home completely, have a completely different look inside of it than it had prior, as opposed to the smallest possible remodel.

Can I write off any of these rehab expenses on my taxes?

1) Appears the property has ungrounded electrical system, not required prior to 1971.https://en.wikipedia.org/wiki/Three-prong_adaptor#:~:text=In%201971%2C%20the%20US%20National,effective%20January%201%2C%201974).2) As a poster alreadsy mentioned, the property may be up to code, just not today's codes. - When building codes are updated, it is often uneconomical for all buildings to be upgraded to meet new codes.

There is a tax benefit and you can welcome him to pay you back but not have an expectation.