Hi,
Can I say,
(a) We brought fruits to him in this evening. We brought fruit to him this evening. Only if you are speaking later in the same evening, eg after you left him.
(b) We brought fruits to him in the morning / afternoon / evening. OK
"in the morning / afternoon / evening. " are they used as past or present tense? They can be used regardless of the tense.
'Fruit' is much, much more common than 'fruits'.
Best wishes, Clive