Motivated by the exceptional properties of graphene, other two-dimensional (2D) nanomaterials beyond graphene such as silicene have emerged with growing interest. Silicene is attractive for its exceptional characteristics and compatibility with silicon based nanoelectronics.  It is believed that silicene may challenge graphene due to a longer spin-diffusion time, a longer spin coherence length, and a much larger spin-orbit coupling gap. Half-metallic materials and spin-gapless semiconductors (SGS) are highly desirable for spintronics because they provide 100% spin-polarized currents around their Fermi level. Spin filters and spin field effect transistors (FETs) are one of the potential applications of these types of materials. Silicene nanoribbon (SiNR) as an approach to opening a band gap in a silicene sheet is a promising material for spintronics due to its unique magnetic properties. In this study, a first-principle method based on density functional theory (DFT) is used to investigate the stability, electronic, and magnetic properties of edge hydrogenated and fluorinated SiNRs. Edge functionalization of all possible types of SiNRs such as armchair, zigzag, Klein, reconstructed Klein, pentagon-heptagon, and the combination of the edges are studied.  It is found that edge fluorinated structures are much more stable than that of edge hydrogenated. It is also discovered that tri-fluorinated Klein edge SiNR and di-hydrogenated armchair edge SiNR are the most stable structures when the edges are terminated with fluorine and hydrogen atoms, respectively. While, the symmetric edge functionalized zigzag SiNRs show antiferromagnetic semiconductor behaviour. Considering spin-polarization, the asymmetry in edge functionalization bring various and extraordinary magnetic states, such as SGS, ferromagnetic metals or semiconductors, and antiferromagnetic metals. In order to discover the effects of doping on the magnetic and electronic properties of edge functionalized SiNRs, N- or B-doped SiNRs are considered. It is revealed that the dopants energetically prefer to be substituted with Si atoms at the edge of SiNRs. Interestingly, the remarkable SGS and half-metal character, as well as ferromagnetic metallic behavior are observed in N- or B- doped armchair, zigzag, and Klein edge SiNRs which are highly advantageous for spintronics applications. These new findings encourage further experimental investigations in the development of SiNRs based nanoelectronics with spin tuning.