I've just been to Sapporo Station to see my mother off.

Literal

Mother [object-を] see-off-[purpose-に] Sapporo-Station [to-に] went-and-came-back-[just-now-ところです]

見送りに = 'to see off' (purpose). 行ってきた = 'went and came back' — てくる in past marks a round trip. ~ところです = 'have just (done)' — marks the action as very recently completed. 札幌駅 = Sapporo Station.