Are you obligated to buy on a wholesale?

[Brittany Smeek]

I am trying to run through the whole process of wholesaling but need a clear answer since I keep finding different ones.

Bianca is about to lose her house to the bank. She reaches out to Tom for a potential buy.

Tom researches her house and finds that her area is $150k - House is in good shape.

He offers Bianca $100k to buy the house. They sign an Assignment Contract stating that Tom can buy or may have the right to sell his contract to another buyer. (correct?)

Bianca gives him 21 days to close.

A) Now, lets say Tom does not find another investor to buy within the 21 days, is he OBLIGATED to buy the house for $100k now? or can he walk away empty?

B) Tom has found a an investor and offered him $125k for the house. He brings his contract to the closing attorney (correct?) and they handle the transaction leaving Tom with a profit of $25k?