“Laith, our grandson, in Apa’s lap,” Rubana wrote in the post on Wednesday.
Rubana also said she was sharing the photo as “rumours about Annis continue to brew”.
The mayor has been undergoing treatment in the UK for cerebral vasculitis since early August.
He fell ill on July 29 after he went to London ahead of the birth of his grandchild.
“It is extremely unfortunate that some quarters gain from spreading “fake news”. Just to assure everyone that HPM, Sheikh Hasina couldn’t have been kinder to us. Not only did she meet with us in London, I personally met her a few days ago when I was in Dhaka,” Rubana wrote.
“Our family continues to be extremely grateful and indebted to her for the extra ordinary support she has offered during our times of distress.
“I hope this picture will kill the rumours and I hope that all of you will continue praying for my husband, Annis,” she concluded the post.