"Property" in the context of an IT38 is the legal concept of property, rather than physical property (eg. a house).
For the purposes of Capital Acquisitions Tax (CAT), property can be understood as anything capable of being owned, including tangible and intangible assets, rights, and interests. Essentially, if something has value and can be transferred or inherited, it falls within the scope of "property" for CAT purposes.
So, when the form asks about the value of property, it means the value of what you inherited, the 1/4 interest in the house.