Adaline was born on 1st January 1908 and so would have been 107 years old (assuming the film is set in 2015) and stopped aging in 1937 at the "age" of 29.
Adaline is 100-something years old, and her daughter appears to be 90 years old
As you say, she was in a her mid-twenties (lets say 24) when she gave birth so her daughter would have been born in 1932 and would be 83.
EDIT: On watching the movie, Adaline was married in September 1929 (age 21) and gave birth 3 years later...so age 24 as previously assumed. Nailed it!
Ellen Burstyn WAS born in 1932...so she's age-appropriate.
Ellis Jones's father (William), the jilted lover is played by Harrison Ford was born in 1942 and so in 2015 was 73.
It's stated that Ellis's parent are celebrating their 40th wedding anniversary and although we do not know how old they were when they got married, their late twenties / early thirties would not be out of line.
William met Adaline in England when he was a soldier studying medicine overseas so that would tend to match up with late 20's/early 30's allowing for college, medical school and time abroad before returning to the US with Adaline.
EDIT: In the movie he claimed to have been in his 2nd year of med school and aged 26. Thus, the character is at least 66 years old and allowing time to meet, court and marry his wife probably nearer 70. Thus Ford's real age would not be out of line with the supposed age of William.
Adaline's old lover's son is in his late 20's.
Ellis is played by Michiel Huisman who was born in 1981 making him 34 in 2015...which would match up, more or less, with his parents being married for 40 years.
It all hangs together quite nicely allowing, perhaps, for a couple of years leeway here and there.
