Yes, Maurice Sendak is dead. Sendak died on May 8, 2012 in Danbury, Connecticut due to complications from a stroke. Sendak was 83 years old at his time of death.
If you mean Maurice Gibb, co-founder of the Bee Gees, he died in 2003.
Maurice Gee, New Zealand writer ( born in 1931) is stiil living, and writing, in Wellington, NZ.