Whats wrong with my baby's dad's MOM?

during the time i was pregnant my boyfriends mom always was talking about when her granddaughter was born she was going to be doing all kinds of things with her like taking her to get pictures and babysitting her and all those kinds of things grandmas do...but now that my baby is here...his mom acts like she doesnt even want to babysit my daughter for an hour. for example, we took her over there and forgot her bottle so we were going to get one and bring it over there but his mom was like "well she isnt going to be over here THAT long" like she doesnt want to babysit her AND she NEVER comes over to see her grandbaby and she lives in the SAME NEIGHBORHOOD. but i guess she complains that her granddaughter doesnt "know her" wtf??? OPINIONS?!?