In the 1910 Kansas City, Jackson Co., MO census William E. (age 22) and Mary C. Rockhill (age 21) are living at the same address as Mary Catherine Reese's parents Lester L. & Catherine Reese. William is listed as "Head" and Mary C. as "Wife" even though they're at the same address as Lester who's listed as "Head". I'm assuming that Mary is his daughter. If I could find a marriage record for her and William E. Rockhill it might confirm this. When I found the same information that you posted above I assumed that either Mary had a second husband named Riker or that Rockhill was a mistake by the census taker. I'm trying to figure this out. I don't know why William & Mary would use an alias. Of course, it could be this is a totally different family just living at the same address.