。
Please help welcome Mr. Nomura.
Literal
Nomura-san [obj-を] welcome-[nom-の][obj-を] help-[request-てください].
Two nominalized actions: 歓迎するのを ('the welcoming of Nomura') is the direct object of 手伝う ('help, assist'). 手伝う takes the activity helped with as a direct object via を — 勉強を手伝う ('help with studies'), 仕事を手伝う ('help with work').