This was not a capital murder, which usually occurs during the course of another specific felony, or requires multiple victims.
The crime of murder in Texas is the same whether it's a premeditated assassination, or a sudden urge to knock someone's head off.
The sentence for felony-murder is 5 to 99 years' confinement or life imprisonment.
Capital murder requires that the defendant intended to kill while committing one of a prescribed list of felonies or that the victim was a member of a prescribed class (police officer, children under 6 ....).
Exactly what charges does Mallard face?
Murder 1, murder 2, (felony ?) hit and run?Murder, with a possibility of LIFE in Prison. She plead GUILTY to tampering with evidence but not guilty to murder. If she gets is found guilty of murder (VERY likely, imho), the max is Life in Prison (crosses fingers that happens). She could be eligible for parole in 40 years. She'll be an old woman before she is out.