Hi, Welcome to Health care magic forum.
Most probably the cause may be the compensated heart failure
, and may have became uncompensated in the process of delivary. The other cause may be the eclamptia, expected to be started during delevary. and after delevary there is rise in hypertension
when there is agitation if B.P is examined she would have been saved. If it is cardiac failure she would have need the E.C.G.
May her soul rest in heaven. Thank you.