Flow of electrons(current) are from higher potential to lower potential, hence during negative half cycle flow of electrons would be from neutral to phase via load.

Dear Shirish Tirthkar,

During the negative half-cycle, the neutral will have greater potential than the supply phase. The conventional flow is from high to low potential, then in this half-cycle, current flows from neutral to phase in closed circuit (formed by the single-phase supply, the load and the phase and neutral conductors ).

Best Regards.

In addition to what said by Desai and Galhardo, based on the load type, in case of the resistive load, the +ve half cycle of the current is typically coincided to the +ve half cycle of the voltage (and also their -ve half cycles are typically coincided). Thus, in case of the resistive load, exactly throughout the -ve half cycle of the voltage, the current flows from the neutral terminal to the line terminal through the load. However, in case of inductive or capacitive loads, since the current is shifted lagging, or leading respectively, the current may pass from the neutral to the line through the load in a portion of the +ve half cycle and a portion of the -ve half cycle of the voltage wave form. The attached Figure shows the voltage, the current, and the power wave forms in case of any load type. We do not say that the current is flowing from load to source rather than we say that the current - since is alternative - flows always from the source to the load but with reversible directions. Similarly, the resultant power flows from the source to the load. In the Figure attached, in case of the resistive load, the power wave is all above the horizontal axis, thus power flow has a unity direction. Contrarily, in case of the theoretically pure inductive or pure capacitive load, power flows in both directions, but the resultant power flow is zero. That is because the pure inductor or pure capacitor idealy save energy and pass it back to the source. Practically, power wave in case of an RL load has a positive portion of power wave with higher amplitude, that is due to some energy is changed to say motion.   

Dear Shirish,

Neutral is a wire which is maintained at a potential close to zero. Remember all the utility supplier grounds the neutral at the generators end. By doing so, he is maintaining the potential of the neutral wire at zero, right? The potential of the other wire, that is, phase is measured with respect to neutral ( zero potential).

Now, during the positive half cycle, the phase will be at a higher potential as you told and the neutral is at zero. Power flow is from the higher potential to lower potential.

During the negative half cycle, the neutral remains at zero potential, but the phase now will be negative potential, i,.e., the neutral is at a higher potential. The direction of current is reverse now. 

But in both the cases, the power flow is from the source to the load only.

Dear Shirish,

Flows from neutral to phase through the load.

current flows from neutral to phase