# Theudas rose up

Possible meanings are 1) "Theudas rebelled" or 2) "Theudas appeared."

# claiming to be somebody

"claiming to be somebody important"

# He was killed

"People killed him" 

# all who had been obeying him were scattered

"all the people scattered who had been obeying him" or "all who had been obeying him went in different directions" 

# came to nothing

This means that they did not do what they had planned to do.