Although I am a REALTOR® and not a wholesaler, I would strongly advise you to talk to everyone you can.

It's usually easier to qualify for commercial, so if a bank approved you, I'd say there's a strong chance.Rates are usually higher in the commercial sector.

I don’t think you are experienced enough yet to purchase an old home from a wholesaler without strong knowledge of house construction, materials, and knowledge of what “issues” to look for.

Sure it's nice to pull up my brokerage account, see them cute green arrows, and listen to talking heads shout "Strong Buy!"

Perhaps a bridge lender would be more inclined to finance as long as you had a strong business plan. 

You manage the property for her, it's a long-term commitment, and what goes wrong with the deal is ALL ON YOU.Just ask yourself what could go wrong and how you'll be forced to resolve it to maintain a strong relationship with your MIL.

Depending on how strong your contract is, you could potentially take legal action against them for breach of contract if they sign with someone else and/or back out, but that is costly and takes a lot of time.

I'm not sure if the best practice for that is to just have a partner go visit, to build a really strong and trustworthy team, or if it's just crazy altogether.  

Still strong numbers (in the mid 20%!)

I do not have strong knowledge on these subjects, and was never taught about them from family, or school.