How can the sentence "I have suggested her to return in the morning" be correctly rewritten?

The sentence "I have suggested her to return in the morning" employs an incorrect structure. The correct form involves using "suggest" in a way that conveys a recommendation, which is effectively done in the option where the phrase is converted to "I suggested that she return in the morning." In this construction, the use of "that" introduces a noun clause, clarifying the action being suggested and ensuring it's grammatically accurate. This reflects standard English usage, where "suggest" is typically followed by "that" plus a subject and base form of the verb, effectively expressing the intention.

The other options may introduce unnecessary changes or use structures that are not conventionally standard. For example, "I advised her to return in the morning" implies a more commanding tone rather than pure suggestion and does not correct the original grammatical issue. Similarly, "I recommended she return in the morning" while acceptable, changes the verb and slightly alters the nuance. Lastly, "I suggested her returning in the morning" uses a gerund incorrectly, making it less suitable. Thus, the accurate choice maintains both the meaning and the proper grammatical form.