"I also saw he said the "true Lallans" died out with his grandmother."

Lallans is simply an alternative name for "Scots" which is the traditional language of the Lallans or Lowlands. The demise of Scots has been talked about for several centuries now but it is still alive and kicking in every day life. The more conservative dialects can still be found over much of Scotland in the likes of the farms and factories in the Borders or the fishing ports of the North-East etc.