Can a Muslim eat the things offered to their idols by Hindus?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

It is not permissible for a Muslim to eat what is slaughtered for idols, stones or anything worshipped by non-Muslims.
Imam Ahmad narrated from Sa’eed ibn Zayd ibn ‘Amr that the Prophet and Zayd ibn Haarithah once passed by Zayd ibn ‘Amr ibn Nufayl while he was in Makkah. They called Zayd ibn ‘Amr to eat with them. Zayd replied: "O my nephew! I do not eat what is sacrificed for stones. After that the Prophet was never seen eating what is slaughtered for stones. Sa'eed said: "I said to the Prophet you know, as my father was so, and you know if he had been now alive he would have followed you, and believed in Islam, so please ask Allah's forgiveness for him. The Prophet said: "Yes, I shall ask Allah's forgiveness for him. He will be resurrected the Day of judgement as an Ummah (a leader having all the good righteous qualities), of a nation."

The Quran clearly forbids eating the animals sacrificed for anything other than Allah. Allah Says (what means):

• {…and those which are sacrificed on stone altars, and [prohibited is] that you seek decision through divining arrows. That is grave disobedience.} [Quran 5:3]

• {He has only forbidden to you dead animals, blood, the flesh of swine, and that which has been dedicated to other than Allah. But whoever is forced [by necessity], neither desiring [it] nor transgressing [its limit], there is no sin upon him. Indeed, Allah is Forgiving and Merciful.} [Quran 2:173]

Imam Al-Qurtubi said while interpreting the saying of Allah {sacrificed on stone altars}, this means every animal, slaughtered by a pagan, maggi, atheist, etc. without Allah's name mentioned on it while it is being slaughtered.”

A pagan sacrifices for an idol, a maggi sacrifices for fire, and an atheist does not believe in anything so he sacrifices for himself. There is no disagreement among Muslim scholars that what is sacrificed by a maggi for his fire and a pagan for his idol is forbidden.

Allah knows best.