Earlier studies show frail seniors often experience loneliness and depression. Moreover, frailty can lead problems with medication and nutrition patterns. The availability of family care and/or nursing care at home is limited. Digital companions, such as social robots, could complement homecare nurses, thereby improving the quality of care to frail seniors. The Guardian project has co- designed with end-users, a social robot providing social company and health support. To assess the digital and co-created solution, usability evaluations have been conducted with 43 participants distributed as fairly as possible between frail seniors, family carers and professional nurses; in three different European areas: The Netherlands, Italy and Switzerland. The goal of this study is to evaluate if the GUARDIAN solution is accepted by the target users and also gather data on how to improve the system for ensuring added-value in home care. The iterative method based on user-centered approach put the end-users at the centre of the usability evaluation. Through thematic analysis of the qualitative datasets, we conclude that a high number of users accept the solution and describe it as useful. End-user needs have been mainly addressed but some new improvements have been pointed out by the participants and some other needs have been uncovered.