My parents were offered a 5 year land contract with an option for 5 more. As they get closer to signing the contract the contract now has only the option for 5 (no more 5 year extra).

They are doing a land contract because they were foreclosed on. What are the chances of them getting financed in 5 years from now? What are the back ups if they don't have the option to reset the 5 year land contract a few years from now?

Any advice you could give would be helpful. I feel like they don't know enough about it to make an educated decision!

Many land contracts are sold so that people can ask more for their property than it is worth, and/or get higher interest than normal.
Also many sell it under contracts so they can take them back over, many make their money selling the same property over and over and getting to keep the larger down payment. Thus the 5 year with no additional years, if they can't get a loan in 5 years, then they will just lose their property, or end up just renting it.