my opinion your guilt is over not visiting your grandma so the only cure is going to be visiting your grandma..

suggestions -

visit by letters... write her a letter or email that she or her care takers can read to her.

visit her by flowers... send her some flowers with a note /card.

visit her by telephone... dial her number /room number or nurses station and see if someone can either put the phone to her ear/ bring her to the phone or let her know you called just to say Hi.

and then the next opportunity you have go see her. take something with you that will make the time memorable and enjoyable.. my grams loves IHOP food, looking at photos (she has trouble seeing so I blow them up to outrageous sizing and sometimes just for comedic affect I sometimes photo shop them into funny mirror affects) Sometimes my gram and I work on her recipes and memories book. One time I was with her and she was telling me a funny story and I said you know grams I aught to write this down and "grams recipes and memories" began. She told me to not tell anyone else what she and I are doing so that the day she wants me to hand out these notebooks to the whole family. her legacy to us. After I come home from my visits with her I hand write her newest story into many binders for each family member. one of my siblings is helping grams do her quilting, another one is teaching her how to do paper crafts (oragami, making snowflakes, scrap booking...)

You cant change the past but you can change the future...treasure your grams while shes here and you will be able to treasure her when shes gone.