In an alpha decay no electrons are created or destroyed. There is a small correction needed for the Coulomb term when the alpha escapes without carrying two electrons with it, but that is at chemical, not nuclear energy scales and is (usually<sup>1</sup>) sorted out by chemical means in fairly short time scales. So, no you do not figure the mass of any electrons into the energy balance equation (or equivalently, you have the same number before and after). --- [1] There are some situations in which ionization can remain for "long" time scales (many milliseconds at least), but these conditions generally require considerable effort to create in the laboratory (low impurity environments and the like).