Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What grand finalist had a year after 1979, a margin smaller than 30, and winners of essendon?

### Inputs:
table_name: table, columns: ['Year', 'Winners', 'Grand Finalist', 'Scores', 'Venue', 'Crowd', 'Margin', 'Season Result']

### Response:
SELECT Grand Finalist FROM table WHERE Year > 1979 AND Margin < 30 AND Winners = essendon