Mumbai is much connected to many cities making travel easy and very very safe for solo travellers. With ongoing summer you could explore these spots
Nainital
Manali and Shimla
Ooty and Kodaikanal Munnar and Asthamudi
Lambasinghi and Araku valley
Pachmarhi
Coorg and kudremukh
Leh Ladakh
Gulmarg and sonamarg
Darjeeling. If you don’t mind the heat but ready to venture here are some more spots
Goa
Gokarna
Pondicherry
Cochin
Bangalore
Madurai
Udaipur Some offbeat spots just in case you might like to explore
Dhanushkodi
Kanyakumari
Shillong
Mcleodganj Dharamshala
Kasol
Wayanad
Chikmagalur Dalhousie
Lepakshi
Kumarakom. Happy safe journey.
I recommend you to travel seven sisters or my favourite Coorg....in Coorg you can find best adventures...many spices with marital men and beautiful women and hospitality is must there ....Coorg is also known for ever green rainforests etc....so i suggest for Coorg to try best adventures and lost yourself in the arms of nature...and feel blessed by communicating with the honourable people there....you can even know the reminiscing past of Coorg and Kodavus/Coorgi people