Feinstein grants daughter power of attorney amid family finance fight, but remains in Senate despite health concerns

Sen. Feinstein gave power of attorney to daughter Katherine Feinstein to handle legal matters.
Katherine Feinstein filed lawsuits regarding Feinstein's access to late husband's estate for medical costs.
Disputes involve selling a beach house and accessing life insurance funds from the estate.
Feinstein's mental lapses have raised questions about her fitness to serve, but she has not resigned.
Feinstein relies on staff assistance but remains influential in the Senate at age 90.