What decides the range of FM band?
The government decides the frequencies.  In the United States, it's decided by the FCC in coordination with the ITU, which is the international governing body (since radio waves don't magically stop at the borders of countries).

There's nothing particular about FM that makes it more suited to those frequencies compared to others.  In fact, ham radio operators and others use FM on many different frequency bands.  Probably when FM broadcasting needed some spectrum, the 88 - 108 MHz was the most convenient at the time, for technological or political reasons.