Some really good suggestions. Its a little touchy depending on how the FH is and how the family is. I want to have a table of family members who have passed on in memory of as 2 of my grandparents won't be there who have passed away in the last 5 years and my sister which is really hard on me and he said its not a funeral he has a hard time sharing his feelings about his grandparents whom passed away before I came into his life. A little off topic but I know at my high school graduation one of my friends gave a speech and included his dad whom passed away 2 years before he graduated and he said I wish I could follow in my fathers shoes and than he said o wait I'm wearing them today. There was not a dry eye in the house. I'm sure your speech will be beautiful no matter what.
My husband's parents passed away when he was young. In my speech i had said "I also thank the giuding stars along with (MIL name) watching over us as she smiles upon us today". It was very special to him and to all of your family members passed away. I hope that helps
My FHs grandmother passed away in March, a few months before we got engaged. He was her best friend so I'm 100% mentioning her in my speech. I think it's a great idea for you to mention his mother, I think he will really appreciate that from you and it will bring her into the wedding a bit more for him.
Its a touchy subject... My FHs father also passed away 5 years ago so i understand where you are coming from. Family milestones (like weddings) are definitely more emotional than normal because his absence is blaringly obvious. I would say it really depends on your FH and how his family will react because everyone is different. Some people may find it very sweet and happy to include her in your speech, but if your FH is anything like mine he may not want those feelings of loss to be any more prominent than they already will be on your special day. Im giving my FH free reign on the inclusion/exclusion of his dad on the day of. If he doesnt bring it up, i wont. And i will be skipping the father/daughter dance because i know my FHs sister would take it really hard... As would his cousins who also lost their father to cancer. And also my dad hates dancing and it would probably be really awkward anyway.
You could mention what a great job she did raising him and how even though you never met her, you know she would be so proud of the man that he has become. You could tie in some memories he has or things him and his mum used to do. Payign tribute to her would be really special.