Question

她担心祖母会消失,于是她点燃了所有的火柴.

Answer 1

worry about后不跟从句的,跟名词或名词性短语,用动词worry后面跟从句是可以的

最好用现在分词作伴随性方式状语：

Worrying that her grandmother would disappear,she lit up all the matches.