Galadriel is sympathetic to Gandalf's explanation that he is afraid and the hobbit gives him hope, and thus offers her assistance, promising that if he should ever need her help, she will come.
He is afraid. Galadriel is sympathetic to Gandalf's explanation this. The hobbit gives. Him hope. The hobbit thus offers her assistance. She will come. He should ever need her help. The hobbit thus is promising this.