Visitor Visa - B2

Hi. I want my grandmother (mothers mom) and uncle (mothers brother) to apply for the B2 visa to come visit us in NYC from Bangladesh. What do you think the chances will be for them to get it? I know my mom can apply for her mother to come stay here permanently but that process can take awhile. I'm 25 and i came to NYC when i was 2. My uncle has a tuition business back in his country and a wife so he has all the reasons to go back home and not stay in NYC for too long. I really have high hopes they'll get approved as long as my uncle stays confident in the interview. BTW he is in his 30s. Also both have no travel history. So I don't know if that will be a huge factor. Also my mother is sick so my uncle can just simply say his coming to NYC with his mom to visit his sisters family and for tourism and he'll go back to Bangladesh asap because his business and wife is there. Hope you guys can give me any extra tips before we start the application. Thanks