The given sentence talks about a place,especially the direction.
We can determine the correct answer with the help of logic and by eliminating the incorrect answer.
We can eliminate options A and D as incorrect answer as 'in' and 'till' are not used to show direction.
'At' and 'To' are used to indicate direction but 'at' is used to indicate the aim. 'To' is used to indicate the direction to a place.
Hence option b is the correct answer.