Grandma Janelle (August 16, 1912 - May 21, 2008) was Danny Jr.'s grandmother, Danny Sr.'s mother and Jared Six's great-grandmother.
Despite being over 93 years old and not knowing what the TV show "Alf" is, Danny refers to her with love, before adding that she's "OLD AS FUCK!". She is never seen on camera, but is mentioned in three videos: Once when Danny is talking to her over the phone while watching TV; once when Danny is talking about her; and once at Danny's son's graduation party, when Danny is talking with his father and Danny's son suddenly enters, stating that Danny and his father both needed to move their cars to create an opening for Grandma Janelle to leave, much to their annoyance.
In a video most likely uploaded in April 2005, Danny mentions that Grandma Janelle is 93 years old. This means that Grandma Janelle was most likely born in 1911 or 1912. She was still alive on May 27, 2007 (at Danny's son's graduation party, when Danny's father visited) as Danny's son mentioned that she was leaving (only resulting in annoying Danny and his father). She would have been at least 95 years old by then. As she has not been mentioned since then, it's possible she could have died.