The correct answer is Option B.
COULDN'T is the negation of COULD.
COULD is the past tense of CAN.
CAN means the ability to do something.
The given sentence is in the past tense.
In the given sentence the speaker was not able to travel by train because he/she reached the station late.
Thus COULDN'T is the correct answer.
The remaining options are incorrect because:
CAN'T is in the present tense.
WON'T is the contraction of WILL NOT.
WOULDN'T expresses the desire to not do something.