It also takes time, don't be in a hurry your grandfather passed away, grandma is in a bad mood is normal, time is the best medicine, you have time to spend more time with her to talk about what she sees and hears every day, do not have to deliberately go to comfort her, talk about daily life interesting things, and even ask her to help do some chores, so that she has a little something to do she will be faster to come out from the loss. Should be more communication and exchange with him, and take her outside to go for a walk, take a break, let her go outside for a while, travel tours including with some of the former good friends to do some of the things they want to do, more to participate in some collective activities, more people at home, accompanied by more detachment you also have to pretend to have passed the sadness, every day is very happy, this is not to say that grandma passed away can not be sad, but in the Grandpa in front of these sadness can not show, you have to let him feel that you have gone through this sadness, then he will also try to live happily.