  Two of the most widely studied extensions of the Standard Model (SM) are $a)$
the addition of a new $U(1)$ symmetry to its existing gauge groups, and $b)$
the expansion of its scalar sector to incorporate a second Higgs doublet. We
show that when combined, they allow us to understand the electron-like event
excess seen in the MiniBooNE (MB) experiment as well as account for the
observed anomalous values of the muon magnetic moment. A light $Z'$ associated
with an additional $U(1)$ coupled to baryons and to the dark sector, with
flavor non-universal couplings to leptons, in conjunction with a second Higgs
doublet is capable of explaining the MB excess. The $Z'$ obtains its mass from
a dark singlet scalar, which mixes with the two Higgs doublets. Choosing
benchmark parameter values, we show that $U(1)_{B-3L_\tau}$, which is
anomaly-free, and $U(1)_B$, both provide (phenomenologically) equally good
solutions to the excess. We also point out the other (anomaly-free) $U(1)$
choices that may be possible upon fuller exploration of the parameter space. We
obtain very good matches to the energy and angular distributions for neutrinos
and anti-neutrinos in MB. The extended Higgs sector has two light CP-even
scalars, $h'$ and $H$, and their masses and couplings are such that in
principle, both contribute to help explain the MB excess as well as the present
observed values of the muon and electron $g-2$. We discuss the constraints on
our model as well as future tests. Our work underlines the role that light
scalars may play in understanding present-day low-energy anomalies. It also
points to the possible existence of portals to the dark sector, i.e., a light
gauge boson field $(Z')$ and a dark neutrino which mixes with the active
neutrinos, as well as a dark sector light scalar which mixes with the extended
Higgs sector.
