What does Gauri mean?
From the Sanskrit गौरी (gaurī), 'fair, white, brilliant'. It is a classic epithet of the goddess Parvati, consort of Shiva, in her radiant form.
What does Riddhi mean?
From the Sanskrit ऋद्धि (ṛddhi), 'prosperity, success, abundance, good fortune'. In one Puranic tradition Riddhi is a consort of Ganesha (paired with Siddhi), though Ganesha's marital status varies across texts.