Ime so sorry dont feel guilty hold your head up high you did more than could have been expected ime not a professional but in a way you have slowly lost your mum over six years and in a way have already greived to a point your nan was very quick you didnt have time to come to terms i lost my partner very suddenly and even thoe now i cant have done more at the time it felt like i had failed her by not saving her from cancer with grief seems to come guilt the what ifs is truely the worst words in the human language but this guilts just your mind running on emotion not lodgic it will go but takes time when these intrusive thoughts come into your think of a great thing you did its breaking that cycle .maybe try some counciling talking to a professional may alay your guilt just take it easy it gets eisier as time goes by. Paul