The word that stands out in that question is "civilize." Civilize is defined as "To reclaim from a savage state." That term implies that the Ibo had no civilization and were savages, but that's clearly not the case. Their society had a justice system and social norms that generally worked. Was the system perfect? No. Certainly there were member of the society such as Nwoye and Ikemefuna and Ezinma who the Ibo culture failed. There are others such as Nwakibie and Okonkwo and Obierika who thrive. That's true of any society. However, if you're asking whether the District Commissioner civilized the Ibo, I would point out that he lied to them and tricked them, he disrespected their beliefs, and he dismissed the entire tragic tale of Okonkwo as worthy of no more than "a reasonable paragraph." The very fact that the closing line of the book is the Commissioner's imagined title for his book, "The Pacification of the Primative Tribes of the Lower Niger," suggests that the whites do not civilize but rather pacify the clan.
Now, are there those who are better off in the new society of whites? Absolutely. The twins and Nwoye are the classic examples of that. But others are left confused and isolated. And many, like Ezinma were poorly served by the old system and will be poorly served by the new one.
My final conclusions on the whites:
Change? Yes. Improvement? For some. Civilize? Absolutely not.
This question is an opinion question, but Achebe gives us several indications of his feelings on the subject through the experiences of the characters. When the missionaries first come into the area, their interactions with the tribe does improve the lives of some of the tribesmen. The outcasts are accepted by someone, and the missionaries rescue the twins that are cast out by the superstitious tribesmen. Others in the tribe, such as Nwoye, don't feel they fit into the tribe and are converted by the missionary message and the church that welcomes them instead of rejecting them as the tribe does.
Unfortunately, early missionaries and colonizing governments did not accept everything about the tribesmen. The new government brought new laws, completely disregarding the laws already established by the tribe. The District Commissioner would send men in to arrest tribal members who broke the white man's laws. These men would be tried before a white man's court, even though they did not understand or agree with what was taking place.
In this novel, Achebe accurately portrays the clash of cultures that existed when established countries began colonizing. With the act of civilizing the Ibo, the British did bring some humane practices (rescuing twins, etc), but they destroyed the culture of the Ibo. "Was the clan better off before the colonizers came in?" - yes and no - Achebe shows the complex struggle that has existed for African tribes such as the Ibo.
how did the district commissioner trick the ibo men?