Can dummy claim points for honors in contract bridge?
Yes. Either hand, by either side, may claim honors. The only restriction is that the honors claimed must all be in the one hand. This has been the rule since before I first learned the game in 1963.

From The Laws of Rubber Bridge (2014):


  PART VII - The Score*
  
  Law 72 - Points Earned
  
  A. Trick Points ...
  
  B. Premium Points Either side or both sides may earn premium points. Declarer’s side earns premium points ..., by holding scorable honors in either of their hands, or ....  The defenders earn premium points ... by holding scorable honors in either of their hands. (see Law 81) 
  
  ...
  
  Law 81 - Scoring Table
  
  ...
  
  HONORS

Scored above the line by either side

For holding four of the five trump       100
honors (A, K, Q, J, 10) in one hand

For holding all five trump honors        150
(A, K, Q, J, 10) in one hand

For holding all four aces in one hand    150
at a no trump contract