PLEASE HELP land contractor buyer dies, son squats. What do i do?

[Brandon Handel]

Hey guys, I need your help. I have the opportunity to buy a house really cheap in an area that'll appreciate like crazy in the coming months. I have one potential problem though. There's a squatter. An investor friend of mine gave me a lead on the house. Here is the basic situation.

Seller "A" sold a home to Buyer "A" via land contract. Buyer "A" died and now his son (we'll call him buyer "B") is living in the property and not paying anything. Seller "A" sold the paper to another person (we'll call him Seller "B"). So now I have the chance to buy the contract from seller "B". My question is If I buy the paper will I be able to evict buyer "B" since he was never on the contract, or do I have to go through the foreclosure process? Does the contract become void since the father died or does the son still have a claim to the house and I, therefore, have to foreclose on him first? 

I've never been in this situation so please excuse my ignorance. My investor friend said I could do either, but since the guy isn't a tenant and not under a lease, I don't know what direction I need to go. Also, I don't know if he automatically inherits the rights to the house since his father passed or not. 

Any advice would be much appreciated!! Thank you!