Is it permitted for husband to bring flowers to wife who is in shloshim like he usually does erev Shabbos?
This would be permitted. The prohibition to give presents to an avel during shloshim is based on the prohibition of Shielas Shalom, inquiring about their well being and warmly greeting them. Here however the flowers are bought to beautify the house for Shabbos, and are not a present for her per say. In addition there are those who permit Sheilas Shalom on Shabbos. Flowers for Shabbos may arguably be included in that exemption. Finally, the Aruch Hashulchan notes that the minhag is to be lenient for Sheilas Shalom during Shloshim, and small presents then would also be permitted.