This all depends on the context of how this data is to be used; and whatever business rules apply to it.
One of my projects has a need to pull documents for a specific date, and the data has from/to just as yours and there are some null
values in there.
The business states that anything that has a null from date is good for all dates prior to the "to" date, and any null to dates are good for any time after the from date.
So the method used in my case is Coalesce (you could
My stored procedure looking for this is similar to this
DECLARE @DateDesired DATE = '04/15/2001'
WHERE @DateDesired >= Coalesce(FromDate, '01/01/1900')
AND @DateDesired <= Coalesce(ToDate, '12/31/2500')
I hope this and the article below helps you determine how you will handle your situation.
COALESCE (Transact-SQL) - SQL Server | Microsoft Docs