Mother is . . . . . . . . home.

Solution (By Examveda Team)

"At" is used to show a specific point or exact location, which is why we say "at home".
When referring to someone's presence in their house in a general sense, the correct and most natural preposition is "at".
We do not use "in home" or "on home" because "home" is treated as a special place word, not just a normal building or structure.
Therefore, the correct sentence is: Mother is at home.