It depends on the content of the options. If it is necessary, that the user sees option1 only for informational reasons you should not hide the option when option 2 is not available. But to show options when actually there is only one option seems strange to me an might be frustrating if the reason for the disabled option 2 is not obvious. In this case i would show an informational text rather the an radiogroup with only one option.
If it is the case that option 1 has no informational value to the user, I would hide the whole radiogroup.
There is another problem. What if the user does not fill out your form in the meant order an chooses option 2 and after that fills in the condition changing value? You would have to change option 2 into option 1 which is confusing. Both mentioned solutions will resolve this problem.