The optimal way to combine the sentences with a participle phrase is option C, which uses 'Meandering through the grove' at the sentence's start and correctly follows punctuation rules.
The best way to combine the given sentences using a participle phrase is option C) Meandering through the grove, Robert and I relished our divine surroundings all the day long.
This sentence effectively uses the participle phrase 'Meandering through the grove' at the beginning of the sentence to modify the main action, which gives it a sense of immediacy and engagement.
Additionally, when a participle is positioned at the beginning of a sentence and acts as an adverb, a comma usually follows it, as seen in this option.