Answer
The conservation of energy law would not be violated.
Work Step by Step
An electron has a rest energy of $0.511~MeV$
A neutrino has a rest energy of approximately $1\times 10^{-7}~MeV$, so two neutrinos have a total rest energy of approximately $2\times 10^{-7}~MeV$
Since the rest energy of an electron is greater than the total rest energy of two neutrinos, the remaining energy can be transformed into kinetic energy of the two neutrinos.
Therefore, if an electron decayed into two neutrinos, the conservation of energy law would not be violated.
