Every situation is unique and there is not a one size fits all approach to protecting your mother's financial security, but there are some options that each has an upside and a downside to.

I never though about eBay for buyers thats pretty unique thank you I will let you guy know how it goes here soon!!! 

Love the idea of pursuing your home inspectors license - that will give you a unique perspective on your REI career.I'm not super familiar with the south TX area, but it sounds like you've given a lot of thought to your strategy and the neighborhoods where you want to execute.

- property management fee (someone has to manage this property, even if your self managing you need to pay yourself for your time) I would use 8% for a property management fee ( there is a whole litiany if charges such as placement fees etc that get charged as well but to keep things simple let’s use 8%) keep in mind your area might be unique i would call some local PM’s to get a feel for the cost.

Very specific situation I've got here that I haven't been able to find good information online that fits this unique criteria.I have a friend that has a property that they own free and clear of mortgage, yet they are paying a HELOC of approx. $300 a month for.

If it didn't sell, they kick it over to their rental division.

This is really unique situation, the residential properties near by has different use, therefore not good for comparables. or do I let them do their market research any way?

I think a broker is a good option, particularly for a unique or challenging circumstance such as the one described above.

what I find very unique right now Ned is the amount of HML or private money companies led by large hedgefunds investing in these HML companies have driven these private rates down to 10% apr or less.. so to only have about a 4% spread between bank money and HML is quite unique in my experience over the decades.. other than the high interest mid 80s anomaly.. 

That being said, real estate does offer some unique tax planning options.