Answer:
C. intend
Step-by-step explanation:
Intend is to have the intention, to want to do something. We could easily say "If you WANT to visit your grandmother...", but not the other words provided as answer choices.
A. contend mostly mean "compete" or "contest", as in "oppose". Not the intention described here, because of the indication of the visiting hours ending soon.
B. assert is mostly demanding something or affirm it strongfully. Neither apply in this context.
D. retort is to reply to someone. In this case, no indication it's the case.