I see no resemblance.
Does everything you find on the web -- including Ancestry.com -- have credibility? If you do, just stop reading this.
And no, it doesn't look "an awful lot like her" -- the photo you posted looks to be a woman about 40-50, with a different facial shape, makeup and styled hair. By that time, Ann Dunham was quite, um, rotund, with long hair, not given to makeup or hairstyling -- in fact, she simply looked like a much plumper version of Ann Dunham/Obama/Soetoro from earlier (attributed) photos.
Please visit the officially unofficial website of Obama, including photos of Ann Soetoro/Sutoro in Indonesia, ca. 1988-92. There's nothing surprising about these photos, since she looks like a much plumper version of Ann Dunham/Obama/Soetoro from earlier photos attributed to the Obama/Soetoro family.
Do you see a likeness to the photo you posted? Do you see any other (sourced and attributed) photos on the web that look like Ann Soetoro with that hairstyle? If so, please post -- and "attributed" means just that -- not some anonymous, unsourced blog, or something posted by a contributor at Ancestry.com -- where anyone who pays their dues can virtually post anything.