Taking over my parents house in NC

My parents own a home in NC and I have been talking to them about buying the house from them for 2 reasons. 1. When they do eventually pass or if they ever need to move to an assisted living facility it's one less thing to have to worry about. 2. It has appreciated in value and could eventually leverage the equity to start acquiring more properties in the future. 

My question is what's the best way to do the transaction. Is a Sub 2 possible so I can keep their low interest rate? Is it possible to acquire their exiting mortgage? Or what other options make the most sense? New to the RE investing game. Thanks in advance!