I think a copy of the quran according to the (calligraphy style and line number that the man prefers). that way you're giving him somehting very nice and suited to him. keep in mind that many people prefer a specific line number per page (13 vs 15 vs 16,17,18 the last three are not so common) and a specific script type (urder/pak/turkish vs arabic/madinah/uthmani).
that way he will always be reminded of his wife when picks up the mashaf.
Also someone asked what gift should I give to my daughter on her wedding day, Imam Shafi (rah) replied give her a copy of the quran. granted physical copies of the quran were probably treasured and much more rare then, but the importance of the book and what it represents, is still the same.