Q. Is it permitted to visit the ill and do Bikur Cholim on Tisha Beav, since it is prohibited to greet people on that day? Should one wait until after chatzos?
A. Poskim permit Bikur Cholim when needed (Halichos Emes p.191 and others).
Horav Shlomo Miller's Shlit'a opinion is that when possible one should wait until after midday.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a