Voltage regulator for 0.1mA load, with lowest possible power draw
There are lot of Low Quiscent Current regulators available on market. CHeck the specifications of GND current, Quiscent Current.
One of them are 
1. ADP160/162/161  - 560nA
2.TPS780xx series  - 500nA

there are other regulators with 1uA Quiscent Current like NCP551/NCV551, some from microchip also.