I very rarely comment on these posts but feel compelled to post in OP defence. Firstly, I have 3 dogs and 8 cats so could be considered an animal lover. However, when my DC were little, my in-laws had a dog which wasn't used to children but, when we would visit, not only did it stay in the room but also was not allowed to be moved from the sofa so someone could sit down. Also, if one of DC went to stroke said dog, they were told to leave him alone by my in-laws. Needless to say we didn't visit very often. What I'm trying to get at here is that I can see both sides of the dog issue.
However, I think people are focusing too much on the dogs here and not enough on the relationship, which is what I think the OP wants help with. Nobody seems concerned that OP arranged to visit DS & DIL, made a drive he/she didn't want to make but wanted to see her family so made the effort and, when she arrived, there was nobody in as DS had "forgotten" to tell DIL. I am assuming the dogs didn't travel with OP, so how much more effort can he/she make? All the OP wants is to have a relationship with the DGC but it seems DS & DIL have a problem with this. It seems to me that, whilst DIL may genuinely have an issue with dogs around DGC, it is being used as a reason not to spend time with OP.
I'm not sure how to go about resolving this as OP has already made the effort to visit DS and family but if you're nervous about driving and travelling some distance to visit and nobody is in when you do plan a visit, I know I wouldn't be too keen to repeat the exercise.
Good luck OP and I hope a solution can be found.