Fatima is not at home at the moment, She . . . . . . . . work.

The preposition 'at' can be used in multiple contexts, such as telling time or location (e.g., telling someone to meet 'at midnight' or 'at the coffee shop'). However, 'at' can also be used to introduce prepositional phrases that identify the object of a sentence.
Example: He was looking at all the different options.