Yes you can freeze sauce that is made with sour cream.
You can make the sauce and cook the sauce and then add the sour cream and freeze the cooked sauce with sour cream.
Or you can make the sauce, add the sour cream and then thaw it and cook it later.
Sour cream is okay to freeze but sometimes the longer the sour cream is frozen the texture seems to change.
Sauce made with sour cream will last up to a year frozen but it's best to eat the frozen sauce made with sour cream within a few months of freezing it.
The longer the sauce and sour cream remains frozen the less fresh it becomes.
I have kept sauce made with sour cream frozen for 6 months and it was still okay.
Then I just put it in a sauce pan to heat the sauce and sour cream back up.