I haven't seen a 1910 census, but on the ones I have seen, there is no date given for naturalization. The box next to immigration status is the year of immigration. Are you certain that the 1890 refers to date of naturalization and not date of arrival?
If Beniamino did indeed naturalize, you need to search for naturalization records. Check with NARA, which holds many of the declarations, petitions and oaths. I believe their office on Varick Street in NYC holds records for NJ as well as NYC.
http://www.archives.gov/northeast/nyc/
From their site:
Where can I find Naturalization Records?
Pre-1906:
Prior to 1906, any "court of record" (municipal, county, state, or Federal) could grant U.S. citizenship. As a general rule, the National Archives does not have naturalization records created in State or local courts. However, a few indexes and records have been donated to the National Archives from counties, states and local courts and are available as National Archives microfilm publications. See the list of this county and state microfilm available.
For pre-1906 naturalizations:
Contact the State Archives for the state where the naturalization occurred to request a search of state, county, and local courts records.
Contact the NARA regional facility that serves the state where naturalization occurred to request a search of Federal court records
Naturalizations After 1906:
And this is what you are hoping for:
After 1906, the courts forwarded copies of naturalizations to the Immigration and Naturalization Service (INS).
Naturalizations from Federal Courts are held in the NARA's regional facilities for the Federal courts for their area.
The National Archives in Washington, D.C. holds naturalization records for Federal Courts in Washington, D.C.