var modis=ee.Image('MODIS/006/MOD13Q1/2018_09_30')
  .select(['NDVI', 'sur_refl_b03']);

var vi = modis.expression(
    '(BL >1500)?0:((A==-3000)?0:(A*0.0001))', {
      'A': modis.select('NDVI'),
      'BL':modis.select('sur_refl_b03')
});

var geometry = ee.Geometry.Rectangle([79.5, 20.4, 81.8, 21.7]);

Map.setCenter(80,20.5, 8);
Map.addLayer(vi, {min: -1, max: 1, palette: [
    'FFFFFF', 'CE7E45', 'DF923D', 'F1B555', 'FCD163', '99B718', '74A901',
    '66A000', '529400', '3E8601', '207401', '056201', '004C00', '023B01',
    '012E01', '011D01', '011301'
  ]});

Export.image.toDrive({
  image: vi,
  description: 'Gondiya_NDVI_30Sept',
  scale: 250,
  region: geometry,
  fileFormat: 'GeoTIFF',
  formatOptions: {
    cloudOptimized: true
  },
  maxPixels: 1e12
});