My mother 64 yrs suffering from severe global lv hypokinesis with ef 20 what is her life expectancy.

Depends: This should be discussed at length with your mom's cardiologist, obviously with her permission. Life expectancy is always difficult to predict and one should never remove hope. Some of the discussion will revolve around the cause of her heart disease and also on possible therapy.

Limited: If she is having symptoms despite optimized treatment interventions it sounds that her prognosis might be very poor (for example might qualify for hospice -> only her doctor can say). It also depends on current interventions, ask your mom's cardiologist for more information and if he/she doesn't feel terminal stage yet but still suffering from symptoms ask for a palliative medicine referral.