It appears Charles F BARTLETT died in 1920s, but his son Charles F Jr was alive in 1930 (and there is a Charles F BARTLETT who lived recently in Columbia, MD)
The 1900, 1910, 1920 and 1930 census all have Emma reporting that she is a widow and born in MD. In 1900 census she lists all three sons: Charles F b Feb 1880; Grover C b Oct 1884 (which is within a month of John B G C BARTLETT in WWI Draft Registration.); and John b Aug 1887.
In 1910 Emma reports only 2 children living, which means John b 1887 probably died by 1910. It looks to me like her 1900 son Grover C, took on his brother's name, and by 1910 was called John B Grovel Cleveland BARTLETT....
Doesn't it look like John B G C BARTLETT married Caroline E KAPPES?