Which grave on reboot hill belongs to granny smith's favorite granddaughter?

I can't give you the exact answer since its randomised, but I can work you through the hints.

First the ghost lady will tell you her age (95 on mine), or find her age from her grave. You can find her grave easily, it's the only smith grave on the right. From that you can get her age, birth date and death date.

The easiest clue you get is that they died at the same age as name (Becky). There are several Beckys, write down their death years. Now check every grave on the left that isn't Becky, only bother with the ones who died at the same year as a Becky.

Once you find someone who isn't Becky but died in the same year as one, check their name against the other hints. Is their first name longer than the last? Does their name end in a vowel? Whatever name hint you got, check this person with it. She will also have given you a hint, saying that she was around a particular age when they were born, check that too (For example if she was born in 1800 and was around 40 when her favourite granddaughter was born then you should look for someone born around 1837-1843) If the person passes all this, write down their name, and try to remember where their grave is.

If you get to the end and only have one name you are done, if you have two or three go back to their graves (hope you remembered where they are), look at the graves near the person for any of her daughters graves. They should be easy to find as the birthdays will be around 20 years above the ghost lady's birthday maybe a little less (I got one at 1816, meaning she had a daughter at age 16) if you can find a daughter next to one of your names it's not the right person.

You should be left with the right name if you have done it right.

The devious part about this puzzle is that it can not be solved without guessing with just the information available at Reboot Hill. There are two completely unrelated locations where critical hints are found: Fort Cowardice and Kellogg Ranch.

Using the hints from these two additional locations, you can find the solution by typing the names, birthyears and deathyears into a text editor and eliminating all which don't match the hints:

"Died the same age as poor Becky, who was always in poor health":

When you examine the graves, you will notice that there are multiple Becky Smith's. Which one is the one with poor health is revealed by the hint at Fort Cowardice. Check the personnel records in the administration building. You will find a Becky Smith with a large number of missed days and no remaining accrued sick days. Check the year of the "B:" and "Dec:" dates. This is the "Poor Becky who was always in bad health". Remove all women where the difference between birthyear and deathyear doesn't match.

"Was born when I was between Age X and Y":

When you go to the right, you will find the grave of the grandmother and notice that she is born in 1800. That means you can eliminate everyone not born between these two years.

"Not buried next to one of my daughters":

Look for the four women who were born the earliest. These are the four daughters. The women buried in the graves left and right from them can be eliminated. And while we are on it: We are looking for a granddaughter, not a daughter, so these 4 women can also be eliminated.

"Her first name ends with a vowel":

Remove all names not ending with A, E, I, O or U.

"Her first name has more letters than her last name":

Self-explaining: Eliminate everyone who has a first name with 5 letters or less, but this hint is actually redundant because of the next hint.

"She liked knitting":

A locked locker in the Dormitory at Kellogg Ranch has an old diary of a "_______ Smith" who mentions that she has relatives with poor health and likes knitting. This is the granddaughter the riddle refers to. The description of the diary gives you an even more precise bound for the length of her name.

When you use all these methods of elimination, you will be left with just one name.

Oh, and if you wonder if this is worth your time, the reward for all of this is:

An offhand item with +11 Spell Damage and sell value of 40 Meat.