momentum of electron e carrying current I and mass m is

current in a given direction is defined as the rate (w.r.t. time) at which electric charge crosses a surface that is perpendicular to the direction. In the case of a single electron, the charge crosses the surface for just an instant of time. I=dq/dt, dq=e, but

dt→0, implying that the current is infinite for the instant of time when the charge crosses the surface, and is zero at all other times. Therefore in this context the concept of current is not defined at all. therefore momentum is also undefined and the question itself is invalid.