Yes, obviously a long neck would be able to dig a trench and lower a body of their loved one down.... I didn't mean it like that. I know that they are animals, even if they are cartoons and thus have human qualities but they are limited.
From observance of elephants for example who are large animals; when a member of their herd dies, they have been observed to bury the deceased with rocks or branches (mainly branches).
Whilst offtopic; I know what the TLK says. I've watched it so many times that I don't have to watch the film to know the words:
-But dad, don't we eat the antelope?
-Yes simba, but let me explain, when we die our bodies become the grass and the antelope eats the grass...and so we are all connected in the great circle of life''..
By Mufasa's words, that does not mean to imply that when the lions die then that is it. Same with Grandma longneck's words about the ''Great circle of life'', doesn't imply that they don't do anything about it...
When we die, we are placed in a casket...we rot, casket rots...we still go to the grass and give back to the earth..by that, it doesn't mean that we don't mourn and bury our dead in a way that we just leave our dead to decompose.
Thing is, in the fandom area (which I base it on two fandoms: TLK and LBT), it's all speculation and theory, there can be no right or wrong as it has not been clearly stated this is what happens.