Well Anandi is not bound by the society.If she gave a thought to what people say about her she wouldn't have retained her relationship with Singhs nor would she have moved in with Singhs.
Her life after her husband died left her no scope to think about herself.There have always been too many things happening in her life she always had her plate full be it before Skhekhars left or after she shifted to Jaitser. She had to take care of her son search for her lost baby and all her remaining time and energy was diverted to SN.
Anandi had enough and more things to keep her occupied.Tomorrow even if her children move away having grown up she will have enough to keep her occupied.She may be alone but won't feel that she is leading barren existence or won't feel lonely because she ensures that she doesn't have time to think about herself.
Mangala may have been illiterate but nobody has stopped her from going out of the house or coming in.Nobody stopped her from having a life for herself.In her society - temple is a place to socialise and meet women like her and she could have actively involved herself in temple related activities.Temples and other places of worship do involve themselves in lot of charitable activities.Illiteracy is not hinderance there.She could have done something for herself in that set up but she chose to lead an empty existence If having someone to care for is the only thing that gives her purpose she should get married again.