If this does not happen the seller could walk with your hard work, equity, and money.

There are many strategies, BRRRR, subto, seller finance, fix and flip, live and flip, and land splitting are just a few off the top of my head.

The only other options I can see are A) your mom partnering with you rather then selling the property to you - you become 50% owner and bring the funds and management to the rental while she provides the existing equity as her contribution; or B) your mom lending you the rehab cash out of her personal funds while also seller financing the house to you. 

I recently watched a video on social media that mentioned the way he was buying properties and yielding the benefit of the sellers low interest rate is having the seller put the property in a trust and then purchasing the trust.

You can present an offer that aligns with your financial goals, but be prepared to walk away if the seller won’t negotiate to a price that ensures you’re not left in a tough financial situation.

However, the success of this approach hinges on consistent appreciation, which depends on demand.The Key Factors to ConsiderPrice Dynamics: Prices are driven by the balance between buyers and sellers.

There are some pockets in this lower price range but they are hard to find and sellers won't let them go for the price you want often. 

Quote from @Joseph Spear: So I just want to take this opportunity to give a shout out to my realtor, who helped make this all possible, Tyler Lingle.He was instrumental, not only in doing a fantastic job negotiating with the seller, and closing on the property in well under 30 days, but he also made the deal possible from the very start.

Attract investors, tenants or sellers?

While not my main area of practice I represented a Brooklyn credit union lender, some buyers/sellers and a few landlords in real estate transactions and rent arrears cases.While we had successes and some failures along the way I ultimately concluded that I wanted to do something different with my life and cashed out of the business.