Of course, she is in peace. It's we who need peace. We should better say, Mary, (my salutes to her), the honored Mary, or simply Mary (a.s.) which means alayihas-salam = salutes upon her.
PBUH (Peace be upon him)
It has become customary to write PBUH (Peace be upon him) after the name of the exalted Prophet Muhammad.
For a few centuries, the Mullahs and their blind followers have been translating Sall-Allahu 'alayhe wa-sallam as "Peace be upon him". Of course, peace is upon him and he is in peace. Does he need our prayers? It is the Mullah who needs peace; peace from propagating sectarianism, hatred, terror, the barbaric manmade Shari’ah and N2I, the Number Two Islam.
Sall-Allahu 'alayhe wa-sallam means, "Allah honors him and supports his Mission."
As a token of respect, I suggest writing: The exalted Prophet, the Prophet (S) or Muhammad (S). We may also write, “Our respects and salutations to him” where appropriate.
Please note that the so-called ‘Durood-e-Ibrahimi’ recited in the Namaaz is nowhere found in the Qur’an. The Bible, the Qur’an and history tell us what great tribulations the Israeli progeny of the exalted Ibrahim had to undergo among themselves and at the hands of foreign invaders. How can we pray that we undergo the same devastation as they did?