 Here is the Python code for setting up a combined fluid-kinetic simulation using the DREAM library with the specified settings:

```python
from dream import *

# Set up the simulation
sim = Simulation()

# Set electric field strength
sim.setElectricField(0.6)

# Set electron density
sim.setElectronDensity(5e19)

# Set temperature
sim.setTemperature(1e3)

# Set up ion species 'D'
ion_D = IonSpecies('D', 1)
sim.addIonSpecies(ion_D)

# Disable hot-tail grid
sim.setHotTailGrid(False)

# Set collision frequency mode to ultra-relativistic
sim.setCollisionFrequencyMode('ultra-relativistic')

# Include Dreicer and avalanche
dreicer = Dreicer()
dreicer.setRate('neural network')
avalanche = Avalanche()
avalanche.setMode('fluid')
sim.include(dreicer)
sim.include(avalanche)

# Set initial profile
sim.setInitialProfile(1e15)

# Enable runaway electron grid with specified parameters
runaway_electron_grid = RunawayElectronDensity()
runaway_electron_grid.setRadialPoints(50)
runaway_electron_grid.setMomentumPoints(100)
runaway_electron_grid.setMaxMomentum(0.5)
sim.setRunawayElectronGrid(runaway_electron_grid)

# Set advection interpolation method
sim.setAdvectionInterpolationMethod('flux limiters')

# Set initialization method
sim.setInitializationMethod('isotropic')

# Set radial grid
radial_grid = RadialGrid()
radial_grid.setMagneticFieldStrength(5)
radial_grid.setMinorRadius(0.22)
radial_grid.setWallRadius(0.22)
radial_grid.setNumberOfRadialPoints(1)
sim.setGrid(radial_grid)

# Set solver
solver = Solver()
solver.setMethod('nonlinear')
solver.setVerbose(True)
solver.setRelativeTolerance(1e-4)
sim.setSolver(solver)

# Include fluid effects
sim.include('fluid')

# Set time stepper
time_stepper = TimeStepper()
time_stepper.setMaxTime(1e-1)
time_stepper.setNumberOfTimeSteps(20)
sim.setTimeStepper(time_stepper)

# Save settings to HDF5 file
sim.saveSettings('dream_settings.h5')

# Run the simulation
sim.run()
```