* Ghani not in building, but family members at home
* Taliban claims responsibility
* Kabul on high alert ahead of April 5 election (Updates death toll, adds another attack)
By Hamid Shalizi and Maria Golovnina
KABUL, March 25 (Reuters) - Taliban suicide bombers and gunmen attacked an election commission office in Kabul next to the home of presidential candidate Ashraf Ghani on Tuesday,...