Go to North East its an wonderful place crime % is nearly zero and lots of places are there for visiting like in assam you can go kamakhya , kaziranga, povitara wildlife santuary and people their are humble one thing u which can irritate you their is food
I would suggest if you wish to travel solo .. any beach places you are looking for it than I would suggest Gokarna.
if any snow places .. I would suggest go to Rishikesh for adventure activities like river rafting , bungee jumping, , than would suggest mussorie to go from Rishikesh which is nearby . Or you can cover Rishikesh & Auli which it's beautiful places to visit .
Rajasthan is quite safe. I went solo to Udaipur and it was great. Pushkar, Jaipur, Jodhpur, Jaisalmer are good options too. I have been solo to Rishikesh and Amritsar and I felt safe. Sikkim is another good option though I went there with another female friend and it was a good experience.
Any place in Himachal would be a good option. You can start with Mcleodganj, Dharamshala..then head on to Bir Billing and Manali...
I travel solo and have always found Himachal to be one of the safest zones.