In such a process the energy is usually released into the surrounding environment if the process is taking place naturally without any external application of force or pressure. Two stable objects will combine only if the resultant state is more stable than the present state.

Hiii sanchita...Two individual liquid drops have a greater surface area than that of a single drop formed after their coalescence. So, coalescence reduces the surface area. As the surface area decreases, energy corresponding to surface area, the surface tension energy, also decreases. Since final energy(after coalescence) is less than the initial energy, energy must be released in the process. Therefore, coalescence of drops releases energy and splitting up a drop requires energy.