In 30 turns make all the ghosts disappear. The grid is separated in the middle by thin walls and gaps. Objects in the central column are unreachable for matches, yet they can be reached via special gifts or boosters. The gifts in those central squares can be made to join the grid by making room in the adjacent squares that are part of the grid.
Priority should be given to the ghosts in the upper rows since that’s where the gift hooks can be found. If the ghosts block those spawning points, then you might find it hard getting rid of the ghosts without any gifts. Boosters can always help, but if you find the top of the grid blocked with no way of dealing with the ghosts in the required time, then it is better to restart the level.
In some playthroughs, you might find a single ghost stuck in the upper most central square. If you can’t activate the striped gift directly below it and can’t hit it with another special gift from the sides, then use a Minebug so you can be done with the objective.