user: Question: What grand finalist had a year after 1979, a margin smaller than 30, and winners of Essendon?
Columns: ['Year', 'Winners', 'Grand Finalist', 'Scores', 'Venue', 'Crowd', 'Margin', 'Season Result']
Types: ['real', 'text', 'text', 'text', 'text', 'real', 'real', 'text']
Sample row: [1977.0, 'Hawthorn', 'Carlton', '14.11 (95) – 11.5 (71)', 'Waverley Park', 27407.0, 24.0, 'Preliminary Finalist']
SQL:

assistant: SELECT "Grand Finalist" FROM "Table" WHERE "Year" > 1979.0 AND "Margin" < 30.0 AND "Winners" = 'Essendon';