She flew to Los Angeles last week, after her 74-year-old mother had a stroke, but is expected to return to Texas in a few days.
she went back to  Los Angeles  by plane 
It does not mention how she returned to Texas. The system only assumes this. 
( z1 go :ARG0 ( z2 she ) :ARG4 ( z3 city :name ( z4 name :op "Los" :op "Angeles" ) ) :direction ( z5 back ) :manner ( z6 plane ) )